A few years back a family of red squirrels got into our 5ver. It was bad news. They chewed through the wiring up in the roof. Thankfully my homeowners insurance covered $1,000 of the $1,100 bill for fixing the wiring.
I got a nice pellet gun with a scope (They run a bit over $100). They loved to climb up into my bird feeder to cram their jaws full of seed. While sitting in the bird feeder I would shoot them. Over about 5-6 years I nailed over 30 of these little buggers. That's the only way to keep them out of my home and RV.
Look for small openings in your RV. They will get into smaller holes than you'd think. I used the spray insulation foam to plug the hole. Right after spraying the foam I would stuff small cut up pieces of steel wool into the foam. They cannot chew through the steel wool.