We made reservations at Falling Waters State Park for the week of Christmas (campsite 3 if anyone wants to visit that week). We made reservations about 3 months ago, and it was difficult finding THIS spot as it seemed EVERY State Park campsite in the entire state of Florida was already booked for this week. It took several days searching, going from web-site park-to-park just to find this one.
So, unless you're parking in a private campground, resort, or someone's back yard, I think you're out of luck with the State Parks!