I use Irish Spring hand soap to keep mice out. I buy the large pack at Costco that contains about 10 bars. Using a sharp knife I shave each bar into about 1/8 inch strip. I put about 6 to 10 pieces into several open zip lock bags. I place I bag into each compartment and place about 6 or 8 around the inside of the coach.
Over the years I have tried several other forms of mouse deterents. .. this is the only one that has worked 100 percent.
Mothballs will keep mice out but the RV will also need to be aired out for a very long time before it is fit for human habitation.
Irish spring is effective without NY terrible lasting stench