I installed the rears without drilling. There's three holes, two of which would be there if you were swapping out the OEM guards. The third requires you to drill a hole. I didn't drill anything for the rears and currently driving them just fine for on road use. They're held in place with just...
They're pretty stiff as you have to bend some angles on them when installing. The shorter the material, the harder it is to bend. I think the full guards should bend easier because of their length whereas something like micros won't.
I just installed mine. Took about an hour to do all four. Once you get one of the front an rear on, then you can do the other side of the truck with no issues.
The rear flaps have 3 holes (identified as the yellow dots in the attached diagram) that don't go into anything (at least for those...