Teetorbilt,
I know this is a pretty old topic, and you may have already painted your whole roof by now..
BUT, have you considered additional attic ventilation to reduce the heat gain? If you are gaining enough heat through the roof to effect your utility bills, you don't have enough ventilation.
We have a black roof on our house, garage, shed. The shed is the best example since it is not air conditioned, but is insulated. One would expect it to be unbearable inside in the summer, but it is actually quite cool due to proper ventilation. We have a turbine vent on it, I do not know if you can use them in Florida I have heard of restrictive codes due to the storms you get.
An acceptable formula in most cases, is one vent (one unobstructed square foot) for every 300 square feet of attic floor space. So if you have two vents on 1500 square feet of attic floor space, you need more vents!!
just a thought.