bathroom floor/rear compartment

[goransons]

Well we found absolutely no water damage in the main living area of the trailer, but that totally changed when we got into the rear. The bathroom floor was in great shape, but when I started cleaning out the battery compartment I discovered that the area had seen its share of water and/or leaky batteries. (guessing the latter as the battery tray was rusted almost completely away) The plywood is pretty rotton inside the compartment, and probably 1" inside the bathroom back wall around the base of the sink and toilet area, but not the main walking surface. I have been reading the rear seperation section in detail, and noticed that when I jump up and down on the bumper there is some flex (about a 1/4 inch or less) between the frame rail and body, and by the pictures you can see some buckle around that area. I'd like to try to repair this section without tearing out the bathroom, as it is in really good shape and I'm not confident the old plastic will come out without cracking. I'm wondering if the wood rot repair would give the floor more integrity or if I can just cut out the rotted section inside the battery box (after taking out the water and drain lines for the time being) without tearing the fixtures out (maybe in two pieces) then attach the body to the frame rails like was mentioned with the 2" L channel. Please let me know your thoughts.