Yuck. we tried dryer sheets, herbal packets, and various other things, but the best bet is 1) find & seal up all the spots where they can get in, and 2) have sticky traps set around the camper - and check it during the winter. Tough when it's in storage, I'm sure, but mice are more clever than we give them credit for, I think.
Good luck!
2020 Toyota Tundra CrewMax 5.7L V8 w/ tow pkg, Equal-i-zer
2020 Lance 2375