Why not make reservations since you know your dates? In doing so, if you get them, you're in. If not, well then you have your answer.
We toured Florida a few years ago in October. Early October we had no problem with getting campsites in the state parks including the Keys. By late October it was different especially on the weekends. They were all booked and we only got in showing up and grabbing a cancellation. We were not always successful.
2015 Advanced RV Ocean One Mercedes Benz Sprinter
Previous Class Bs:
2011 Great West Van Legend Sprinter
2005 Pleasure-way Plateau TS Sprinter