Similar problem 31 Excella
About a month ago got a '81 Excella- 31, and have begun repairs. I've got the same problem with corroded bottom 2" of outside skin at rear, but also cannot see anything of the vertical struts/studs that should be connecting the inner/outer skin to the floor across the full 6 feet of the straight area of junction between wall (under window) and floor. this is a center bathroom model. This trailer was rear-ended on the freeway when still under prior owners usage. Outside skin damage was almost non-existent and I can only assume that the vehicle running into the trailer must have gone up underneath the rig. The accident resulted in destruction of rear bumper and main frame members being bent up. Prior owner had already cut out damaged frame members and re-welded straight replacements. He also removed damaged flooring in rear bedroom and put in new plywood, and on top of that wood laminate flooring. My plan is to remove the inner skin under the window and see what is going on there. Clearly something is missing, but not knowing much about AS's I'm not likely to know what is required there. Any help out there?