My project is coming along well, but I could use some advice on material for the subfloor. I want to use a type of plywood that will sit flat and solid on top of my rigid floor insulation and be a good anchor for studs and screws. The flooring guy at my favorite wood supplier didn't know what kind of wood would work for this application. Whatever I use needs to be able to handle more extreme humidity changes than a typical home, since the bus will be moving around a lot, and seeing a variety of climates.
If you've passed this point, what did you use? Are you happy with it? What kind of plywood works best for skoolies? Do I need to go full-on marine grade?
As always, any help is appreciated.