Workout Rehydration - Gatorade anyone?

During my swims which are always a minimum of 3 hours, I have 3 bottles of frozen water and 1 bottle of Rehydrate from Advocare. Because I swim in warm saltwater, as well as hot temperatures, these are becoming not enough hydration. I then sorta doggie-paddle with my heavy bag of fluids out to the first buoy (75 yds) and tie them down so I can hydrate every half-mile. I don't do Gatorade: too much sugar. Off topic a bit: now that I am in Texas for awhile and not swimming quite as much (only 4miles 4xweek), I have had no foot/leg cramping at all, but in the saltwater of Roatan, it is a constant problem. Maybe my skin is absorbing salt? After all, people wear patches for different ailments and the meds are absorbed that way. Still trying to figure out the cramping problem unless it is still conditioning as I move upwards in mileage.

During my swims which are always a minimum of 3 hours, I have 3 bottles of frozen water and 1 bottle of Rehydrate from Advocare. Because I swim in warm saltwater, as well as hot temperatures, these are becoming not enough hydration. I then sorta doggie-paddle with my heavy bag of fluids out to the first buoy (75 yds) and tie them down so I can hydrate every half-mile. I don't do Gatorade: too much sugar. Off topic a bit: now that I am in Texas for awhile and not swimming quite as much (only 4miles 4xweek), I have had no foot/leg cramping at all, but in the saltwater of Roatan, it is a constant problem. Maybe my skin is absorbing salt? After all, people wear patches for different ailments and the meds are absorbed that way. Still trying to figure out the cramping problem unless it is still conditioning as I move upwards in mileage.