If squirrels didn't have bushy tails, people would call them rats. I pay no mind to folks who say "but their so cute" I had them do so much damage to one of my rigs it took me weeks to repair. They chewed entirely through the main wiring harness on my E 350 based Jayco. That harness is as big around as your wrist and a couple hundred wires. After you splice all those, you won't have any love left for those tree rats. There are a number of ways to get rid of them. Search youtube.
Here's one and there are many others.