I store my SC in a good barn in New York, but rodents are inevitable. I have tried everything--no need to go through the details--but this year, I think I might have found the solution: it's an impermeable, zippered, SC-size bag that you drive the car into and zip up. Comes with four or five big dessicant bags that you throw in first, and you of course make sure you drive into the bag a totally dry car, not one still dripping from its pre-winter wash job or whatever.
They guarantee that the car will come out in the spring in exactly the same condition it went in.
Cost me about $240 including shipping. Bag is of excellent quality, heavy, not just a piece of crap with a cheap zipper on it, and it comes with complete instructions. (Yes, there is a specific procedure...) Go to
www.carvaluesplus.com