Sleeping / Mattress Leveling Platform Build for 2026 4Runner Hybrid

[Gagi]

Starting a clean DIY build for a mattress leveling platform in my 2026 4Runner Trailhunter Hybrid.

As most of you know, the hybrid rear seats do not fold fully flat, so sleeping inside requires a proper leveling solution.

Goal:
Rear-only platform
Flush transition to folded seats
No middle hinge or “book fold” effect
Strong enough for two adults
Removable
Clean factory-style finish

Material picked up today:

SWANER HARDWOOD 3/4 4X8 PREFINISHED BIRCH PLYWOOD
$90.58 at Home Depot

Tools ready:
Router
Saw
Basic shop setup

For clarity, this is a fully custom DIY build for personal use. I am not copying any commercial product or proprietary mounting system. This will be my own measurements, structure, and execution.

I’ll share measurements, cut plan, support structure, and updates as I go.

Photo of the plywood loaded up attached.

Let’s build.

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[HVLA]

In.

 

[mtk_rob]

looking forward to this and to stealing any of your good ideas. i tried to do something similar and am quasi-successful but i do need to pull it out and make some minor adjustments. this is a project i started a while ago and haven't gotten back around to for other priorities, however i found the rear section so useful, i use it full-time.

let me share some of my learnings, starting with the rear section.

1. I initially used my all-weather mat as a template. traced it out, cut it out with a scroll saw. the issue is that a platform that large doesn't fit through the opening, so I had to shave a bit off the right side and make the it somewhat straighter than it would be if i filled every last millimeter of space on the right where there's a pocket of extra room.

2. there is a tension in the height. mine is just under 8 inches, i need to take it down another 1/4" or so, so my mat fits under the battery trim on the left. 8 inches is about the useful height to get bins and things under there. i didn't want the weight of a drawer system and these cheap and ubiquitous clear plastic bins allow me to mix and match whatever gear i need for a given adventure.

3. my vertical supports need to move back several inches in order to preserve access to the little compartment above the rear bumper. same with the compartment at the other end behind the rear seats. minor, but will be a big improvement in terms of storage. mine are filled with recovery ropes and gear now.

4. with the vertical supports moved back or shortened to allow access to the compartment, the one on the right would block access to the built in compressor in the TH and the one on the left is already making access to the battery compartment annoying. so they're both going to need to move inwards towards the center as well. because i'm using some kind of mahogany block plywood i had laying around there's plenty of support and no risk of the edges sagging with people up there. nonetheless some trial-and-error will be needed to get everything dialed in.

5. i'll probably need to do some trimming of my all weather mat once (and not until) everything is finalized.

OK, now onto the front section which covers the seats in the lowered position:

6. IIRC the entire platform is just under 6 foot long when fully assembled but some additional space can be obtained by moving the front seats forward while people are sleeping. i bought this mattress https://www.amazon.com/dp/B0CR6CY1V5 which fits exactly into the space.

7. in this prototype version i used a single piece of plywood for the upper body area that connected to the rear piece with some sliding gate bolts. when not in use that piece can just rest on top of the rear section.

8. however in the next version i believe i am going to rip it into two halves horizontally and connect the pieces with piano hinges (already procured) so they 'accordion' on top of the rear section and when not in use there's a little raised "shelf" against the backside of the rear seats while in use.

the entire thing cost me about $50 since i had the plywood lying around. most of that was for the not-yet-deployed piano hinges, the rest for the gate bolt locks and random hardware.

anyway i hope that is helpful! i am not trying to steal your thread, but if your ideas and plans end up better than mine, i will definitely be stealing those! good luck!

 

[Gagi]

looking forward to this and to stealing any of your good ideas. i tried to do something similar and am quasi-successful but i do need to pull it out and make some minor adjustments. this is a project i started a while ago and haven't gotten back around to for other priorities, however i found the rear section so useful, i use it full-time.

let me share some of my learnings, starting with the rear section.

1. I initially used my all-weather mat as a template. traced it out, cut it out with a scroll saw. the issue is that a platform that large doesn't fit through the opening, so I had to shave a bit off the right side and make the it somewhat straighter than it would be if i filled every last millimeter of space on the right where there's a pocket of extra room.

2. there is a tension in the height. mine is just under 8 inches, i need to take it down another 1/4" or so, so my mat fits under the battery trim on the left. 8 inches is about the useful height to get bins and things under there. i didn't want the weight of a drawer system and these cheap and ubiquitous clear plastic bins allow me to mix and match whatever gear i need for a given adventure.

3. my vertical supports need to move back several inches in order to preserve access to the little compartment above the rear bumper. same with the compartment at the other end behind the rear seats. minor, but will be a big improvement in terms of storage. mine are filled with recovery ropes and gear now.

4. with the vertical supports moved back or shortened to allow access to the compartment, the one on the right would block access to the built in compressor in the TH and the one on the left is already making access to the battery compartment annoying. so they're both going to need to move inwards towards the center as well. because i'm using some kind of mahogany block plywood i had laying around there's plenty of support and no risk of the edges sagging with people up there. nonetheless some trial-and-error will be needed to get everything dialed in.

5. i'll probably need to do some trimming of my all weather mat once (and not until) everything is finalized.

OK, now onto the front section which covers the seats in the lowered position:

6. IIRC the entire platform is just under 6 foot long when fully assembled but some additional space can be obtained by moving the front seats forward while people are sleeping. i bought this mattress https://www.amazon.com/dp/B0CR6CY1V5 which fits exactly into the space.

7. in this prototype version i used a single piece of plywood for the upper body area that connected to the rear piece with some sliding gate bolts. when not in use that piece can just rest on top of the rear section.

8. however in the next version i believe i am going to rip it into two halves horizontally and connect the pieces with piano hinges (already procured) so they 'accordion' on top of the rear section and when not in use there's a little raised "shelf" against the backside of the rear seats while in use.

the entire thing cost me about $50 since i had the plywood lying around. most of that was for the not-yet-deployed piano hinges, the rest for the gate bolt locks and random hardware.

anyway i hope that is helpful! i am not trying to steal your thread, but if your ideas and plans end up better than mine, i will definitely be stealing those! good luck!

Wow you went full throttle. Love the idea of full bed extensions
I’m doing half bed only cargo area.
More photos and measurements are coming soon.

 

[Gagi]

The progress and some photos

 

[Gagi]

Okay, now at the point where I have to determine the best height.
also find out where am I going to position the rail type legs(raisers)
im going to leave the cargo matt underneath.

Let’s gooo

 

[ropdykex11]

great work! watching this

 

[Gagi]

great work! watching this

Thanks.
I just saw the truck bed organizer company called Tmat. Does anyone own one? What the height of it? That could be the best solution for Hyb (if the height matches)
For only $199 , hmm…
https://www.tmat.com/products/tmat-suv-kit-48x48
Anyone?

 

[Gagi]

looking forward to this and to stealing any of your good ideas. i tried to do something similar and am quasi-successful but i do need to pull it out and make some minor adjustments. this is a project i started a while ago and haven't gotten back around to for other priorities, however i found the rear section so useful, i use it full-time.

let me share some of my learnings, starting with the rear section.

1. I initially used my all-weather mat as a template. traced it out, cut it out with a scroll saw. the issue is that a platform that large doesn't fit through the opening, so I had to shave a bit off the right side and make the it somewhat straighter than it would be if i filled every last millimeter of space on the right where there's a pocket of extra room.

2. there is a tension in the height. mine is just under 8 inches, i need to take it down another 1/4" or so, so my mat fits under the battery trim on the left. 8 inches is about the useful height to get bins and things under there. i didn't want the weight of a drawer system and these cheap and ubiquitous clear plastic bins allow me to mix and match whatever gear i need for a given adventure.

3. my vertical supports need to move back several inches in order to preserve access to the little compartment above the rear bumper. same with the compartment at the other end behind the rear seats. minor, but will be a big improvement in terms of storage. mine are filled with recovery ropes and gear now.

4. with the vertical supports moved back or shortened to allow access to the compartment, the one on the right would block access to the built in compressor in the TH and the one on the left is already making access to the battery compartment annoying. so they're both going to need to move inwards towards the center as well. because i'm using some kind of mahogany block plywood i had laying around there's plenty of support and no risk of the edges sagging with people up there. nonetheless some trial-and-error will be needed to get everything dialed in.

5. i'll probably need to do some trimming of my all weather mat once (and not until) everything is finalized.

OK, now onto the front section which covers the seats in the lowered position:

6. IIRC the entire platform is just under 6 foot long when fully assembled but some additional space can be obtained by moving the front seats forward while people are sleeping. i bought this mattress https://www.amazon.com/dp/B0CR6CY1V5 which fits exactly into the space.

7. in this prototype version i used a single piece of plywood for the upper body area that connected to the rear piece with some sliding gate bolts. when not in use that piece can just rest on top of the rear section.

8. however in the next version i believe i am going to rip it into two halves horizontally and connect the pieces with piano hinges (already procured) so they 'accordion' on top of the rear section and when not in use there's a little raised "shelf" against the backside of the rear seats while in use.

the entire thing cost me about $50 since i had the plywood lying around. most of that was for the not-yet-deployed piano hinges, the rest for the gate bolt locks and random hardware.

anyway i hope that is helpful! i am not trying to steal your thread, but if your ideas and plans end up better than mine, i will definitely be stealing those! good luck!

How is the fitting of the mattress?
I was thinking of getting the Lino, or fit the one I have already.
this: https://amzn.to/3MVWuIp
I appreciate your huge support and help. Thanks for your time.
This is why the forums are great

 

[Gagi]

Finished. Cleaned up and applied gloss finish lacquer in the corners and all the sanded areas.
Sharing the pictures and measurements. If you have questions I’d be happy to help.
tips:
- if you have a router that will help a lot.
- Plywood thickness is less than 3/4 as Home Depot advertises. It’s 18mm. For that I ordered a router bit from Amazon fits perfect. One straight cut and done here’s the link. https://amzn.to/3OHiPtQ
Measure the material you are going to use and cut the slits accordingly (test on a scrap)
- I also learned to make two perpendicular cuts at the ends of the foot cuts to have a straight line for the legs(raisers) to fit snag.
Overall cost just the plywood($90.58) the router bit (2x14.99$) and gloss lacquer spray (13.98$) less with my military discount.
enjoy and good luck if you ever decide to try.

 

[RunnerRocks]

Nice work. I like it!!

 

[Gagi]

Nice work. I like it!!

Thanks. Me too

 

[mtk_rob]

nice work. i like how you built your risers. maybe ill rethink the height of mine. that looks pretty comfortable with just a slight incline of the head position maybe a front section isn't necessary at all.

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