New user needs info 36ft 5th wheel

[Hamilton]

I own a 2002 Jaco and my in laws have a 2012 Cedar Creek, and I'm in charge of maint and repair on both. Last year while it was at the deer lease we had rats move in to the cedar creek. Only damage I have found was the tail lights. My front clearance light and the first side marker light on each side still works, but that's all. Does anybody know how these wires are ran through the frame? All wires are good until they go up into a aluminum channel above the water and sewer compartment and I can't find anyway to access them further down the line. I would think they would be in the sub floor, but it appears they drop down from the top of the trailer getting to the tail lights. I already temp retired 2 so I could get it home from our last camping trip but I want to go back and fix everything right.
Anybody ever tried to rewire one? It appears to be an almost impossible task!

BTW, I've done a search and found some good stuff on here, but just not what I need to repair trailer

[dieselguy]

My tail light wires run the length of the fiver inside the street side frame above the belly pan. The upper rear clearance lights run from the same wiring up the back wall streetside as well.