Please don’t forget to account for the rooftop ac units and the air bags of the rv, which also raise the body. What are Dometic ac units, ~18” and bags will give 4” of stroke.
The way I “cheated” was to pour in a 6” curb around the perimeter of the slab. A 2x8 and 2x6 stack horizontally on this. Then, 2x6x14’ walls. I may be an inch off on my 2x’s, it’s been 7yrs. Then my biggest of three doors is 14tallx18wide regular garage door with jack shaft opener. That is my...