Bolting anything through the floor requires a massive mounting plate on the underside to adequately distribute the pressure applied to the plastic barrier and block foam insulation.
Well... HANGING things off the floor, under the rig, such as the LP tank and generator are excepted. Adding things to the top, yes indeed. But dont panic if you look and there is no 'Big plate' under the 'Eurochair'.
I put 7 carriage bolts through the right side floor, between the coach door and passenger front seat. I want to make a battery box that hangs there. LOTS of empty space, and a great spot for that weight.
Here is a photo of one of the bolts, and the 4 holes from the former seat, aka 'Eurochair'

Note that there was no big backing plate. Just washers. The floor there is not 3/4" ply, 1 1/2 " foam and then plastic. Knowing there would be a seat there, the factory built up the same thickness (1 1/2") as the foam with two thicknesses of solid 3/4 plywood. Under the 'top' 3/4 floor. I might also add that installing that one new bolt was VERY different. Drilling through it was much harder then the other 6. And snugging the nut down on the washer did not distort the black plastic at all when tight.
Gotta love thread drift... Maxxair vent topic turns into floor construction.
