Anything that you know about construction, forget it. The way a camper is built defies logic.
I believe that all of the exterior walls are built the same. If you read throughPirates post on adding garage cabinets you can see an open wall. More Garage Cabinets - Page 4 - Dutchmen Owners
Are you actually going to hang something on the wall or are you just wanting to anchor something. I have an aversion to putting any holes in any walls walls in our camper, so if it won't hang on with industrial strength double sided tape, velcro, Command Strips or PL Premium, it has to be anchored to the floor.