Best way to stop mice rodents from entering stored moter home in barn?

i have moth balls but would like to nkow if there is a better solutionBest way to stop mice rodents from entering stored moter home in barn?
I know a guy that swears by dryer sheets. He puts them in his Florida trailer (he's a snow bird...) and said he never sees mice droppings upon his return. He puts a lot of them everywhere! You could experiment and put them in one area of the motor home and leave moth balls in the other just to be safe.Best way to stop mice rodents from entering stored moter home in barn?
my brother has rats in his barn where his motor home was....they ate wiring, hold in the wall, they have tried everything....but finally moved the motor coach out.
get a cat.