I've been pouring through the foamie thread for quite some time and I think I understand that the only places you might need framing is around window, door and possibly vent cut outs. Also inserting hard points where you expect to attach things to your walls.
The one thing that is still eluding me is... how do I attach the foamie to the trailer? Are the walls glued and skinned to a plywood floor and the floor bolted to the trailer? If so I assume 5/8 or 3/4 plywood is what is needed.
I'm kind of stumped on this.