It just goes against everything I beleive to leave a boat outside. I know that you may not have any choice. That is a great investment to let it set out and the weather destroy it.
Have you tried to find an indoor storge facility for it? I was able to find one close to the lake for $75 per month. If you can't do that can you have a metal carport like one of these?
www.carports.com You can get them around here for $795 installed for a two car size. You will have to pay extra for a taller one to cover your boat without lowering the tower. The sides can also be covered to the ground or close to it. Search around and you'll find all kinds of protection hopefully in your price range.
Does it freeze where you are? Do you use your boat year around?