We have never had a mouse problem and we live out in the country. There are plenty of field mouse that want to find a good place to spend winter months. On all my campers over the years I remove anything they can use to make a bed. I also take everything that resembles a food source out and put it it a large plastic tote with a secure lid. I vacuum all drawers, pantry and areas that store food or prepared food.
My son who use to store his camper along side mine decided to leave things in his pass thru compartment like paper towel rolls, wipe rags and a beach bag with beach towels nicely folded inside. In the spring of that year he found nest of baby mouse, urine, poop and a few offspring that did not make it. He ended up throwing away all those items and disinfecting the pass thru floor. The next year he listened to me,
You can look for easy pathways underneath into your camper and using steel wool block those off. No food, no water, nothing to make beds out of along with making entry hard will go a long way in preventing mouse problems.
