I was an IDIOT for buying a Thor Palazzo!!!

I certainly would not default on the loan. It will ruin your credit and the loan company will repossess the motorhome and sell it for what ever they can get for it, which will be way less than you paid for it, then they will come after you for the balance between the loan and what they get for it. You need a good lawyer to tell you the best options that you have. Sorry for your problems but don't make them worse.
JMO,
Ed