Evaporative cooling does not work well in the Southeast when the humidity is usually above 90%.
Water is most important, but water without electrolyte replacement increases the chance of headaches and cramping. Electrolyte replacement without adequate water causes even more serious problems. Products like Gatorade, Cytomax, etc are ok for cyclists and marathon runners, but probably have too many calories for your needs, and still do not have enough sodium or potassium for the volume of water consumed. Also, because Gatorade uses sucrose as the calorie source, water is pulled into the gut instead of being absorbed from the gut. Cytomax is somewhat better, since it uses maltodextrin as the calorie source (three times as many calories per molecule compared to sucrose, so not as much osmotic load for the same number of calories).
You might want to check your local bicycle shop for
electrolyte replacement capsules to take along with one to two quarts of water per hour.