Replacing Walls

People have done this sort of thing. It's a lot of work, but it's not impossible for a handy do-it-yourselfer. If you're hiring someone to do it the labor will make it fairly expensive.

Not infrequently the floor also needs attention as water collects there. If you have wood framing in your trailer, it may well be rotted and require parts to be replaced. (If you have aluminum framing, that's obviously not really a concern.) Expect the project to take longer than you think, if only because the access and working conditions in an RV are rather cramped and tight and there's generally a good bit of finicky fitting etc. to do.

I am going through this very project in my restoration of my 2002 Dutchmen TT right now. It it's quite a simple process and if you are handy then you will have no problems working this out. Just removed the cabinet so you can get to the entire panel. Rip out the old, replaced insulation, replace needed studs and put the new panel back. No special paneling needed. I just bought what was on the shelf at the local hardware store. I'm going to be painting it all anyways so I'm not concerned about it matching right now.