Fort Wilderness is in Kissimmee, Fl. Try the KOA in Kissimmee/Orlando. Also look in Claremont and Winter Garden for RV sites. Try to book Ft. Wilderness in the middle of the week, also try two weeks back, three weeks ahead, you can always cancel. Tell them you want to reserve several time slots so they work with you. Remember you are trying to book during the busiest time of the year. Try different grades of camp sites, they have good, better, best (premium) sites.
You should not have to winterize in Orlando.
Bob & Sharon, "15 Cedar Creek 38CK Custom, '13 RAM 3500 Laramie, 4x4, LB, CC, DRW 6.7 Cummins HO, Aisin 4.10"