I went ahead and cycled that coast to coast rail trail in Florida. Starting in Fort Lauderdale near Miami, I pedaled US Highway 1 north to Titusville, left on Main, right on Canaveral, and there I was on the path in the inky dark. Way too much noisy smelly traffic on 1, and no site for a stealth tent. The C 2 C path was as smooth as silk, mostly, and kept everyone out of the motorized traffic. But here again---a paucity of even a small space of concealment for a small tent for one night. Try being up at midnight and 3 a.m. searching for a spot 9 feet long and 8 feet wide four nights in a row.
By the time I had cleared far north of Orlando and curved south to Tampa/St Pete, I lost the trail, found myself on Hwy 19 south, and cycled that to Hwy 60 in Clearwater. The concentrations of car and truck traffic were never meant to be. With the wind blowing the wrong way, unfortunately, a cyclist can get constant doses of air poisoning throughout the day. Many too many cars and trucks and pollution. In Clearwater I got on Hwy 60 east to Vero Beach on the east coast 60 is doable on a bike, but not so much in Lake Wales where old-town sidewalks and no side lane define your urban landscape. More problems doing a stealth night in the bush.
From Vero Beach to my home town of Stuart and back to Fort Lauderdale was a spin. This was something like 500 or 600 miles. I have not measured it. What is needed is a bicycle / multiple-use trail from coast to coast in the United States.