I can't speak to specifics, since I don't know if there is a Florida law recognizing the red "diver down" flag or they're referring to Coast Guard rules relating to Alpha flags, but we have to consider the implications of the law.
If there's a law mandating a clear 300 foot radius around the flag, how does that affect the rights of vessels in channels less than 600 feet wide, or sailboats with limited maneuverability?
Much importantly, how big does a flag have to be. In order to protect a 300 foot diameter circle a flag must be clearly visible at well over 1,000 feet, otherwise an approaching boat won't have the time or room to execute the required maneuver. (If you don't see this, sketch a diagram and it'll be obvious)
So, if you're looking to the law and enforcement for a solution, be aware that this sword cuts both ways, and consider how big a float you're willing to tow. Also consider whether you would want laws mandating that you tow a float that size.
Consider laws regulating our roads. Despite laws to the contrary, motorists routinely hit pedestrians and cyclists, fines are rarely issued because the motorist has a simple defense - "sorry, I didn't see him until it was too late". Accidents happen, and it'll be small consolation for a diver to know that a boater was fined.
There are two ways to approach life. We can try to modify the world around us, or we can adapt to the way it is. I opt for the latter.
