Dave;
Some ideas for you. 1, Markham park is not free but it is clean and safe with a 100 yd range. Yes they have some strange rules and they are a bit anal about safety (not a bad thing, judging what some unsupervised ranges are like)
2, I've fired at Revere many times. You need to be aware that their ventilation system does not. I mean that there is essentially NO ventilation, save a fan to blow the lead dust around. I strongly suggest using a high quality mask to protect yourself from the smoke and lead fumes. Nice people there however.
3, On the West coast of Florida, just north of Fort Myers, is a public outdoor range that is essentially unsupervised. It has three or four separate ranges, set off for rifle, pistol etc. There is a small fee to use the range all day long.
This range has just recently been re-furbished and is very nice. You can rapid fire, to your hearts content.
4 There are a couple of local clubs with range facilitys here in south east florida. Most are for smallbore and or pistol. no high power rifle. I have not investigated them as they do not offer a 100 yd or more range.
There are no other ranges that I have learned of. If you find one, let me know so I can go and enjoy myself too.
Roger in Tamarac