BikeArkansas-I've tried every trick and like you I still cramp to varying degrees. I consulted my physician to get his advice. I've tried all kinds of supplements, tums, hydrating very well the week before etc. I still cramp......I continue to find muscles in all parts of my legs I never knew existed......and when the cramping starts I often wish those muscles didn't exist!!
Here is what I'm doing more recently and it seems to help some-but it is still not a cure:
Eat at least one banana a day
Hydrate extremely well several days leading up to the ride-keep a water bottle with fluids with you all the time
Supplement V8 Fusion for fluids a day or two ahead of the ride-it has tons of potassium
Take Electrolyte pills a day or two ahead of the ride and the morning before the ride
Drink electrolyte or sports drinks during a ride rather than water-if drinking water use electrolyte pills
Eat several bananas during a ride
Spin easier gears!!
The weather and how hard I push seems to have the most influence on how bad I cramp. Quinine is helpful to alleviate cramping and can be found in Tonic Water and also in over the counter meds called Leg Cramps. However I don't use it during rides. I tried Tonic Water before a ride (per my doctor's advice) and the carbonation wreaked havoc on my stomach. Leg cramps seems to affect my power output and heart rate (quinine has been and is still used for some minor heart issues) so I only use it at night when I wake up with leg cramps.
Good luck and let me know when you find a cure.......I'll be right there with you buying drugs!!