I can recommend sites in the keys... but they won't be available...
When we were in the keys last winter, we made reservations for this year. We were booked at Sunshine key near Marathon for the month of January, but the reservations were cancelled due to hurricane damage.
I tried replacing even one week of that time elsewhere in the key and couldn't find any availability. Miami had a few spots available, Naples is where we ended up instead of the planned for keys.
Sunshine Key has been very cooperative trying to book us at other sites, and they have been prompt in refunding the payments we had made. Maybe next year. (when the rates will be higher due to all of the new or improved facilities...
The bottom-line is that I doubt that there is much available in the keys at this time, and competition for the few sites will be stiff.