Dryer sheets

I have camped in various travel trailers and a 5er since about 1990. I have always parked them next to the woods near the house. Never had a mouse. My parents had two motor homes which was parted closer to their house than the woods and seemed to battle them every winter, even to the point of mice chewing thru wiring. They finally tried some electronic sonic rodent repelers. Something like that. It fixed their problem. Of course, they where plugged into 120 year round.