We had a caravan on a seasonal pitch. We had it stored over winter in a large hanger which was well known for its rodent visitors.
I can confirm that mothballs were excellent. Using the small mesh washing bags, supplied by a well known company, we put four mothballs in 4 separate bags. Each bag was hung beneath the seats at four corners of the van (where the air vents were). They remained solid, with no sign of 'melting'. We did not need to use mouse traps or anything else. Our van came out of storage some months later and there was no sign of any little monsters getting onboard. Our close neighbours in storage also were suprised they had not had a visitation, when other vans in the same building suffered quite badly.
Needless to say, don't leave any food in the van. Even in airtight containers.
There has been a thread on this already, but it is a long time ago so you may not be able to find it. Hope this reply is helpful.
