Hybrid rebuild help

Part of the walls are affected as well as the floor. The floor was just holding water because the barrier underneath wasent allowing the floor panel to dry out. I've already gutted everything in the trailer back to the bathroom and where the wallpaper had wrinkled is several places where I pulled those spots off it just continued to flake until I hit styrofoam. The only reason i havent ripped the bathroom completely out is because i was afraid the walls were working as ceiling support. I think you are exactly right about the floor being composite panels. I'm going to Completely gut everything in the trailer because At this point I really don't have anything to lose. May end up with a flatbed trailer when done. Lol. Im a master electrician and have a HVAC license. I have access to plasma cutters and breaks so I feel confident in getting the trailer back together nicely with advice. But I've never seen anything built this way and would like to limit the damage caused by trying to remove everything. The outside is in great shape I call the camper Dr Jekyll and mr Hyde because what happens when you open the door.