Re: rodent deterrent during storage???
I've been in the RV industry for 13 years now. I was convinced I heard and saw everything.
This year, I heard a new one: Rubber Snake. I haven't seen it proven or even implemented, though. I guess it will work like a scare crow.
Steel wool in all the exposed holes (bilge, drain, etc) will stop the mice.
They chew it, and it cuts up their mouths and they bleed to death.
Mothballs in the vehicle: no doubt highly effective and widely used. I prefer to scatter them on the ground around the tires, tongue jack, and outdrive. Keeps the mice from gaining access in the first place, and keeps the boat/vehicle from smelling like Grandma's closet. There are some moth ball based products (i.e. Mouse Away) that work well, also. No substitute for straight up moth balls, though.
Heard a lot of good and bad about dryer sheets. Show me the proof that they work. Put a mouse in a closed container with a mothball. Put a mouse in a closed container with a dryer sheet. The mouse in the container with the dryer sheet will be much less pissed off. He'll have a comfortable bed, until he starves to death. Oh, yeah - remove your food and vacuum crumbs off the floor and out from between your seats. They're after something when they get in.
The sad fact is that if a mouse or any other critters want to get in, they will get in. A mouse can get through a 1/4" diameter hole. If it isn't big enough, they will make it bigger. They can jump, fall, or be dropped (by a bird of prey) into an open vehicle. In a boat, they will then wiggle under the mooring cover through a vent or between the snaps. The final defense: TomCat, DeCon or other mouse killer inside the vehicle. You don't want to bait them into your vehicle, but once they're in there, you definitely want them dead. Just hope you can find the carcasses.
Defend your territory the best that you can.