This one's got no real villain, just a half crazed guy held prisoner who got violent. There are well meaning scoundrels in Doc's uncle and a native American descendant of Calusa Indians.
It's never clearly delineated in the novel, but I suppose that the man who invented florida is based on Tuck, the uncle. He invented some stuff that helped develop the everglades, among other things. The story is around a miracle spring that Tuck discovered on his land via his horse, Roscoe. (or Rollo). The horse had drank from a spring and the former gelding subsequently grew his balls back. Turned out the spring water was heavily contaminated with some toxic shit. Tuck's plan to sell it was thusly thwarted, but the poison being there prevented the state from imminent domaining his land. They had to clean up the mess first and hadn't got the money for that.
I learned a lot more about Florida: the glades, and so on.