Mesh fabrics vary widely in how much light they actually block. Usually the range is 70-90%. Even a fabric that would block 70% should give your plants a break from the blazing sun. The heat is another story, some plants will not tolerate the Florida heat and humidty, even with shade. It seems to me that at this point in the summer you really don't have anything to lose by trying. You might rig up some supports over your plants with about 12" of head room so that the fabric doesn't contact the plant anywhere. Then drape the mesh fabric over the framework, securing the fabric (I have used tie-wraps for this purpose) to allow for ventilation and watering.
Good luck and let us know how it works.
Cindy