If it's any help, the Tampa/Key West "Bone Island" big boat regatta is this week (May 12 - 16), so maybe your St. Pete race could run through that fleet and just turn left at Marco...

And you could get ground crew at Goodland, Everglades City, Cape Sabel/Flamingo, so your biggest unaided stretch would be more like 40 miles. You can "park" the boat anywhere... just getting outside assistance may be difficult.

For the most part if you're within a mile or so of shore, you do get cell coverage for most of the way (not sure about Cape Sabel to Keys)