We were down to the Everglades last year in Feb. and Mar. with a 25 foot TT and had no problem finding camping spots. Rather than stay in one spot, were toured the State for three weeks.
Buy touring we could see where we would and would not like to stay.
Down the east coast we found several nice camp grounds. Things were a bit busy around the larger towns like Jacksonville and Daytona.
The Glades were nice and we came up the Gulf coast. There were many campgrounds on the Gulf side that were fishing resorts.
My point is, unless you are desperate for a place to stay, you might want to try several areas for a few days to see if you like the area. With a 20 ft. TT you should not have a problem getting a spot.
We used the Good Sam’s website and our cell phone to reserve ahead every few days so we always had a campsite waiting for us.
We put a lot more miles on the TV sightseeing than we did towing.