Last year, our first snowbird season, we sorta went without reservations. We lucked out when a fellow poster on this site posted that he was cancelling a reservation at Oscar Scherer State Park down in Osprey. I jumped on part of the reservation and then another poster offer the dates he'd taken. We ended up with 9 days at the state park. This was the only true reservation we made.
Over a six week period (February 1 to March 15) we traveled around Florida staying at 8 different parks (one of them twice), 7 without reservations made well in advance. Note: Not made well in advance meant we didn't make reservations before leaving Michigan. However, when we knew where we wanted to go next we called ahead a day or two in advance and reserved a 3-4 day stay. We never had a problem getting into our desired park. We even extended our stay at one park from 4 to 7 days because we liked the park, area, and temperatures. We were near Miami and the weather was cooler up north so we decided to stay longer in the warm temps and moved north when Weather.com told us when the warm up was going to happen.
Prior to leaving I did some serious research on campgrounds/parks in areas we were likely to travel. I created a chart with 35 parks on it that listed the address, phone numbers, websites, and some general info regarding daily/weekly/monthly rates, amenities, general comments/ratings I found on RV Park Reviews.com, and directions. This helped us determine where to go next.
We had a great time seeing the different areas of the state. We'll be leaving in about a month for a 2 month stay and have reservations at 6 locations, including 3 state park stays for a total of 11 days and one of the reservations is for a month long stay. Our plans are loose for the first part of the trip because we don't know the exact date we'll leave as it will depend upon the weather along our route south. Last year we left on a specific date and that was a mistake because the weather somewhat bit us in the butt just prior to leaving. We'll give ourselves a window of about 10+/- days to depart and watch the weather forecasts. We'll stay someplace as we work our way down south to our first reservation at Myakka State Park near Sarasota.
Note: Staying periodically at state parks will help reduce your overall expenditures (average per night costs). Also, the longer you stay at one location the costs will be lower as daily rates are the highest compared to weekly or monthly, with monthly the least costly.
Go for it!