The back wall is fastened in 2 locations. At the bottom with staples and at the top where it fits under the metal frame of the trailer. I have my galley at the rear of the camper and cut the wall down at the edge of the galley. On the side opposite the galley is a storage cupboard and I cut down at that side also. The mounting for the spare tire is in this area. When I took the wall down, I had to remove the LPG detector and a wall plug for 120 volt. I went into Home Depot and bought a piece of wall board that matched closely the rest of the trailer. (A picture of the wall went with me to assist in colour mnatching). The wall is mounted under the lip of the top frame and is held in place next to a 1" x 3" x 6' piece of wood fastened and only accessable from the outside of the camper. I had dry rot in this piece and replaced as much as I could. The new wall panel is 1/4" thick and had to be installed in front of this piece. I found a long plastic U shaped moulding and used it to secure the wall board under the lip. I used a product called "No Nails" which is used with a calking gun. I fitted it under the metal lip of the trailer and installed the U moulding with the opening in the down postion so that the wall board fit up inside it. The placement of the wall outlet and the LPG detector is optional as there is lots of wire inside. I also put a 1 x 1" wood piece across the floor to anchor the bottom of the wood panel. I used the metal of the spare tire holder as a guide for the placement of the wood panel, and where there was problems with fitting, I covered with wood trim. The finished product is very close to what it looked like to begin with.
I found that water had entered the trailer where the bunk end was when the bunks were inside the trailer when the lid is lowered.
The rubber seal left a 1/2 inch gap that was between the lid and the box of the trailer. I solved this by getting a garage door weatherstrip (the shape is like a Capital "C" with one long edge on the bottom and a smaller edge at the top. The garage door weatherstrip is the type used for nailing into the bottom of wood doors. I used the no nail calk and 6 self tapping screws to fasten a piece which overlaps on both ends of the bunk to seal the opening. I did this on both the front and back bunks on my trailer. This has completely stopped water from entering my trailer when traveling in rain. The screws I found also at Home depot have metal washers with rubber pads on them. I hope this helps you,
2009 GMC Sierra SLT Crew Cab 4x4 Diesel
2013 Jayco Eagle 28.5 RLS