Ok as far as dryer sheets go. Must be BOUNCE brand. There is something in BOUNCE that no other brand has. Mice will chew right thru other brands. Mice HATE BOUNCE sheets. Also (remember mice climb, they dont fly) Sprinkle a fair amount of moth balls around everything that touches the ground from the RV. Mice despise moth balls and will avoid the area.
As rustic eagle says---Place a bucket of Damp Rid inside the coach, you may place a bucket under the coach as well (especially if storage area is a grass field). Keeping moisture down is the biggest life saver of an RV.
If you decide to cover your RV, make sure the cover is breathable, and will allow the entire area "under the cover" to dry completely. Some covers actually "trap" the moisture.
I started with nothing, and still have most of it left
2001 Jayco KIWI 23B
2003 Jeep Grand Cherokee 4.7 AWD