It's been many years(the 80's)since I was in FL. so I don't know if it holds true now but FL. has county campsites that are real cheap at least they were then ) and they are all over the place , they are fenced in and have good showers. good luck
Even camping at the state parks can be tough in the Keys. Many parks are filled December and January. Everybody is looking for someplace warm. Hopping over to the Bahamas will be expensive with a $300 clearance fee. Best of Luck
Sail it back to DC and stay at the Gangplank marina in DC or somewhere nearby till it sells, or stay in FL if I have reliable income by then. Policies are that you are only allowed to stay there 4 nights a week so I'd have to be out of there on weekends but I can do that.