What Florida asks of a build
Build for water and width, not for altitude. The highest ground in the state is 345 feet and the towns in this guide run from 1 foot at Everglades City to 207 at Brooksville, so gearing, cooling for grades and altitude tuning are all beside the point. What matters is whether the vehicle can cross standing water, sit in heat and humidity for days, and hold a line on soft limerock and deep scrub sand.
Width is the second brief and it is written in the rules. Big Cypress admits a street-legal 4x4 only in one unit; its ATV class stops at 55 inches, its UTV class at 66, and a swamp buggy at 8 feet including tyres with a 6,000 pound ceiling. Decide which of those you are building before you spend money, because the wrong answer is a legal problem rather than a driving one.