Well----I can tell you what DOESN'T work: Irish Spring soap!
Last year I read on an RV forum that pieces of Irish Spring would repel mice. So I bought several bars, as well as some netting fabric . I cut each bar in to pieces, carefully tied them up in each pouch of netting, and placed them in all storage compartments and some interior cabinets.
Fast forward to this spring: My husband brought me a few "pouches" and mentioned that I needed to wrap them better..........I looked at them and noticed many sets of little micey tooth marks all over the soap! Those little buggers had chewed through the netting and eaten the soap!
So much for the Irish Spring Soap Theory!
Guess I'll try something different this year ;}
(Lucky for us--we haven't noticed any other mouse signs or damage)