That’s scary. I’m just waiting on the Cali Raised roof rack, and I really hope they include some instructions. didn't know that was a possibility. Do you think the problem might be with the floor panels?
Never heard of any WD racks causing vibration. Something isn't right. Pics might help diagnose the problem. Just make sure all the bolts are tightened down. Maybe the valance is loose and causing the buffering?
I just looked at Westcott's website and can see how it might cause vibration with all those holes in the floor. Any chance you have a sheet of plywood or luann laying around that you could cut to fit and drop in over the floor for a test drive? It would at least help you determine if the exposed holes in the floor is the cause.
It looks like the floor panels can be removed too...but that is a lot of bolts to be removing as a test.