We skipped around to different FL state parks that offer camping. It was tough to route it as we booked the camping reservations late, so we ended up zig-zagging as follows:

Day 1: St. Pete to Little Manatee River state park
Day 2: Little Manatee to Highland Hammock state park
Day 3: Highland Hammock to Alafia state park
Day 4: Alafia to Lake Manatee state park
Day 5: Lake Manatee to Little Manatee
Day 6: Little manatee back to St. Pete

I used Google Maps "get there by bike" feature and the suggested routes worked great. Be prepared for lots of gravel (shell) and dirt roads while you're is central Fl. Lots of phosphate mining and agriculture .