Rodents (mice) keep infesting trailer and pickup truck ???

You can try spraying a product called Mouse Oust (available online) on the ground outside of the trailer/truck. We have had limited success with it but my MIL swears by it. It has a fairly pleasant mint smell. Other than seal EVERY and I mean EVERY hole, no matter how small. We just had to scrap our house fridge because one crawled up inside the back where we couldn't reach and died.