Keep your camper clean. Before you store it or park it after a trip, clean out the camper. Remove all food and trash. Vaccum the floors and beds. Clean the counters and stove top with a disenfectant. Check cup holders, seats and under the seats for crumbs or old food. Food products attract vermin more quickly than anything else. Remove all clothing, blankets and sheets to be washed, as these may smell of food which can attract rodents as well.
Patch up any holes. Check the interior of the camper first. Look at the flooring, in the corners and within the cabinets. Patch any holes with silicone or expanding foam. This foam expands a lot once it dries, so experiment with something else before you use it on your camper. Crawl underneath your camper and look for and holes. If you can see light, patch the hole. Holes can be present in the body itself or within wiring. Rodents are often tiny, so even the smallest hole can allow them access.
Put your camper in storage during the winter months or when you aren't using it. Either rent a storage facility or use a garage or barn. Try to choose a place that is well sealed. If you store your camper in a in the outdoors or in a rickety shed, you are likely to have problems with vermin getting into the camper. Purchase a camper cover that fits your model. Cover the camper whether you are storing it in or outdoors.
Put mothballs or dryer sheets in your camper. Though the smell might be intense, it is also likely to ward off vermin. If you choose to use dryer sheets, replace them frequently. Once the dryer sheets dry out, they are no longer effective. It's the potent odor or a fresh dryer sheet or of mothballs that really bother rodents. There are also ultrasonic pest devices available. These look like smoke detectors, but they are meant to irritate pests by using high pitched noises.
