I used to live in St Petersburg Fl for 15 years, I currently live in New Port Richey 40 miles north. I have now 10 mutt hens, but used to have up to 50 hens of mostly heavy breeds here in NP Richey. Most of my property is shaded by granpa oaks. That's the key.
You do not need any buildings for chicks here, I use big wire cage with roof, solid back wall and perhaps side wall (wind protection) for night shelter, predator protection (racoons). They do not need any heat or cold shelter in our winters, just shelter from heavy winds, rain and predators.
As for breeds any breed will do, I would avoid heavy legfethered breeds like Cochins and Brachmas, but I know there are Brahma breeders in Fl so perhaps this is not the issue.
If you have no trees you have to provide some shading structure constructed the way it will catch any wind breeze, do not attempt to keep them in full sun. St Petersburg is hotter and more humid in summer than Pasco county where I live now.