Be very careful about the security of the tarp and its frame. A Solstice owner had his car damaged when a similar cover pulled loose in a storm and hit his car repeatedly. His was free-standing, but it is worth taking extra care to ensure that what is supposed to protect the car does not damage it.Around the Chicago northwest suburbs here, renting an enclosed storage unit costs $175 per month, so last year I parked our Sky under our deck. I had mounted a tarp to the underside of the deck which worked but had issues with drainage, more issues than I anticipated. It was also very difficult to setup.
This year I decided to try something different with a new 12x16 tarp. Working with the same wood material, I came up with this which was so much easier to setup. The 1x2's along the lower sides hold it together well, yesterday being a good windy test, but I wonder about 60 mph winter winds. I am thinking of swapping out the lower 1x2's for 2x3's or 2x4's.
Being lower on the sides, this "shelters" our Sky better than last year and drains better with no concerns for the deck itself, but I have to be watchful for blowing snow accumulation.
I place trays of mothballs in the trunk and passenger floor, and hang 3 bags of mothballs in the engine bay in strategic places. I also store the snap-on engine cover inside the car, and plug the tail pipe with a snug-fit plastic bottle. Last year I had no rodent issues using this strategy.