We were up in the panhandle 2 winters ago in Feb and it was not averaging above 70. The conventional wisdom is "south of I-4". The problem is that snowbirders make reservation for next year when they leave this year. Unless there' a cancellation and you happen to call right after, it's tough to find a spot that isn't $100 a night.
John Prince Park in Lake Worth doesn't allow reservations more than 120 days in advance (not exactly sure of the time period, but it's something like that). You may have time to snag a spot there. We stayed a couple of weeks in November and it is a nice park. The area around it is congested and there's a general aviation airport next door (a plus for me), but the place is pretty big and the premium sites aren't all jammed together.