We're the same age and I also prefer riding and training on roads...although the slowly growing number of Rails-To-Trails bike paths are getting a little of my training time because they offer nice scenery.
I may require tossing the bike in a car or onto a bike rack, but getting away from urban/suburban Gold Coasters is going to be your best bet. I've ridden my motorcycles in your area (Ohio Snowbird) and that entire area is a traffic disaster.
One of Florida's problems, as far as road cycling, is finding safe secondary and tertiary roads to ride on. It seems like as soon as they build a road down there, condos follow with the traffic out-pacing the road development. Northern Florida seemed better for riding in my humble non-local opinion.
Again, I would suggest riding with a group, when possible. Your age and speed range should make it it easy for you to fall in with any number of club groups from sportive level to aspiring racers to triathlete types to fast tourists, etc. There is safety in numbers and often more fun to be had than training solo.
I've bicycled the East coast of Florida a time or two and I wish we had your fine weather!