I completely renewed a Lil Bigfoot
a couple of years ago.
I had the same wall covering problem.
I removed all of the interior cabinets including the seats.
I removed all of the fabric and left the foam.
I like the material Scamp
uses and could not find any on the West Coast so I bought it from Scamp
and had it installed by a local auto upholstery shop.
The Rat Fur from Scamp
was about $300.00 and labor was $400.00.
You will have a much better job if you gut the trailer before you redo the walls.