I have the 325RES floor plan so not sure if identical to yours but I also installed the same protector. I unscrewed the 6 or so screws inside the basement and removed the wall to gain access for installation. I was able to see all the wiring and have plenty of room to work. Have you tried going in that way?
2014 Crusader 324RES
2012 F250 4x4 6.7L