If you have a wood framed trailer, the wall panels aren't that difficult to remove. Find the seams, and you can probably get a flat 90* pry bar underneath the panel and pop the staples loose. Same thing should go for interior walls on a lightweight trailer. With the wall open, you have other options and could put in a cripple stud or a plywood sheet to help carry the weight of the TV mount.
If it's aluminum framed, 99% chance the wall panels are laminated around the actual frame so don't even think of removing... An infrared camera might help show where the studs are because there won't be any styrofoam insulation on the studs.