What is the appropriate distance to stop behind another vehicle when stopped at a red traffic light according to the State of Florida?

The state law will probably say a 'safe distance' one rule I've always used, (and it's a good one), is stay back far enough that you can clearly see their back tires where they touch the ground. This will usually provide enough distance. You could check your local rules of the road to see if this addressed in there, other than the 'safe distance'....