You have three choices, these are probably listed in order of expense.
1. Contact a repair place and have them do the repair (boat shop?)
2. Buy a new one from
BigFoot, then put it on yourself or have someone else do it. Have you contacted
BigFoot to find out what once will cost? It may not be as expensive as you think. Or, is it possible it's a generic part... lots of stickies trailers have fender flares.
3. Do the repair yourself.
I'd go with #3. What do you have to lose, but a bit of time and a bit of money? You'll gain experience that will provide skill/knowledge that you may need to put to use for more serious repairs in the future.
I'll leave it to the experts to describe the process of repair.