That’s a great question! Legally there is no requirement, but there really should be. We run a flag on our mud boat and law enforcement always comments very positively. Even boats fishing in the canals should run them.
The higher the better, but you want it at least 10 feet above the water.
Schmidt Aviation has an airboat shop in Pompano (954) 782-2845.
Gator pro sells them on line. https://huntinglight.com/