Hedge apples. Keeps mice and spiders away.
Place a few in something like 1 gal milk jugs. Set several around inside and in the basement.
The hedge apples will soften and begin to rot during the winter with the freezing and thawing so the need to put them in something like plastic jugs. But when they soften and start rotting they put off a sweet smell which not only keeps the critters away but gives the camper a nice smell.
I'm in the country where crops are all around the house and camper. Hedge apples have worked for years keeping critters out.