Phil is correct about concentrated peppermint..all rodents hate the smell.
I live in a Forest (but under cover !!!) and the mice love chewing on fuel lines and certain plastics..many owners have had bills of £5000 to rewire some camper vans parked on site.
My friend works at Nestle chocolate factory in York and for over 100 years they have used concentrated peppermint to keep rodents out of the works.
My Supersports and other vehicles live outside..I have an electrical sonor device in each but also have pots of the oil mixed with water and cotton wool balls when parked for a while.
Very successful.
It is also well known in Motorhome circles that peppermint oils is the best solution.
About £9 for a bottle on ebay...it goes a long way
