Class C Construction Hackery

i think you have a stick-built (likely wood) frame that began atop a plywood deck that was bolted to the steel chassis frame. seems to me that after you find and remove all the bolts/lag-screws as well as figure out all the adhesives and connectors between coach (house 'box') and cab, and disconnect, then, as you stated, some temp framing that will tie studs to plywood floor and which you can get your tractor lift forks under...should work.

there is no standard construction detailing for motorhomes...but if you are seeing wood and not metal studs, your thinking is sound.