Moderation may be the key. It sounds funny but sometimes the most simple of solutions are the best. If you are well hydrated the night before and that morning there is no need to drink lots just before the dive. This has its own problems if you are in a dry suit, as many people are here in Vancouver, Canada. If salt is not available, dilute the juice with one part sea water and nine parts fresh water.
Dehydration is always present with decompression illness.
In looking for the ideal oral rehydration fluid the article compares apple juice, Club soda, Coca Cola Classic, Diet Coke, Gatorade, Ginger Ale, orange juice, Powerade, Snapple Kiwi Strawberry, Sprite, Beer, Pedialyte, Rehydralyte, and WHO - Oral Rehydration Solution. The body continues to be dehydrated for a while after the production of urine increases so keep drinking How to overcome the dry suit problems of needing to urinate during the dive. Large adult diapers are used by some commercial divers. As a recreational diver with limited change facilities this may be awkward but possible. The other solution is a condom catheter.