All last winter I used the sticky pads (---furnished by my home pest control service), placing at least 6 or 7 of them around the inside of the trailer, plus I used two commercial sticky pad mousetraps. The latter are nothing more than sticky pads in a box. The net result was not a single mouse, spider, or other undesirable critter. I also had an electronic pest control device in service - but it was only active when I had the trailer plugged in to recharge the house batteries. Unfortunately, somewhere on our last trip to the Maritimes (Nova Scotia & Cape Breton) we picked up another passenger. He may have jumped ship since our return home but I'm keeping the electronic device in service until I know for sure - or until I can replace the sticky pads. The gist of the story is that campgrounds are prime breeding spots for the little critters and they're dedicated Hitchhikers!
2003 GMC 3500 D/A, CC, LB, 4x4 and 2000 Airstream Excella 30. WBCCI 7074