First question is, was there insurance on the trailer? How long ago did the wheel well destruction happen? If you could get the trailer repaired via insurance, this would be your best bet, even if you have to pony up for the deductible.
If the answer to the above is "no," then, the best bet is to learn how to properly repair the trailer (not rocket science, but there is a wrong way and a right way), and then you will be able to sell it at its max value. If you had to pay someone to do the repair, it may cost thousands of dollars, in which case, selling as a fixer-upper, may be the most expedient way to go.
But, get a reality check. look at eBay completed listings, RVtrader.com, craigslist, etc., and find out what that trailer of yours is really selling for. The value you quoted seems a bit high to me.