When I use to bow hunt my dad would actually take the tent as he made a much more comfortable bed in it then his was in the TT (1970's 14ft Aristocrat). My vote is also for a tent but I would also use a good quality tent. Look at something like Spring bar. I still have the tent mentioned above it actually was my grandfathers. My mom says she can remember it from when she was about 16 so that puts it 53 years old and still going strong.
I would be inclined to repair the floor and ride out the rest of the loan or try and sell it. Like others have said if you customize you reduce the market you would be able to sell it to in the future.
As far as state parks we go to several and have had no issues. I would prefer to boondock, but we go with friend that like the convince of a reservation and water, if the cannot get FHU.
Good luck