Here in Texas we don't have much of a problem with the cold weather so I plan on just leaving my boat outside on my land and I plan on using a billboard tarp to cover it.
If you don't already know, all of the billboards you see around town are made of a single piece of some very very strong vinyl. They even have a seam all the way around them so you can insert a rope and cinch them up. They are also practically brand new, depending on how long they were posted there.
They are also 5 times stronger than those blue tarps from Home Depot.
With the right connections in your town you can get the no longer needed billboard tarps for about $50 to $100.
They are to way heavy to be ship to your city so check
www.craigslists.com (which by the way is an incredible website for used stuff), Ebay etc. or make friends with a guy that works for a billboard company in your area. They will have stacks of them.
They usually are 2 different ones:
14' by 48'
20' by 60'
I have a connection in Dallas but they weigh 80lbs and 143lbs respectfully, but like I said you probably don't want one shipped to your city.
If you need to modify it you can cut it and use a industrial strength heat gun that will melt the seems together .
Overall they are really cool and helpful if your roof gets blown off in hurricane or tornado, but the are heavyyyy.