What material is it made out of specifically? I don't have a shelter so I'm clueless on that.
What area are you in?
I'd try a product called SEM color coat. It's a flexable coating made for flexible and ridgid plastics, carpets or vinyl. They may have a more appropriate product if that won't work.
A lot of professionals use it and I have used it to redo the interior on a early bronco and it came out great.