First seal up anyplace critters can gain entry. Wash the roof and outside. Winterize your water system. Flush water heater and inspect anode rod. Turn off LP valves. Clean the heck out of the interior especially where you store food. Clean fridge and keep doors open. There are a multitude of threads about mouse prevention so best to do a search. Check your tire pressure and inflate accordingly. We place several airboss dehumidifiers (link:airBoss Closet Dehumidifier - Walmart.com
) throughout the camper and leave the roof vents open just a crack. We remove the battery and keep it at home. We also remove all linen and anything that can freeze. I might be overdoing it but I also take our 2 tv's home.