Several years ago, during another one of the gas crisis fiascos, it was determined that we should not waste petroleum to make the insulation for electrical wiring.
The industry switched to SOY based insulation material which saved them a few barrels of oil but unfortunately rodents loved to eat the now edible insulation.
On an RV, as with many other vehicles, and homes, there are a lot of wires that go from one end of the coach to the other end.
I have used both fox and coyote urine, which is available from most online hunting supply stores, to spray around my RV and this seems to do a good job of keeping squirrels and mice away. I spray this all around the wheels and any other thing that makes contact with the ground and would allow rodents to get inside the coach.