Drink lots.
I just take a mouthful or two of water and/or cytomax every 10-15 minutes. Worked for me today.
Camelbak + 2 water bottles.
The key really is to pace yourself. You can't drink too much at one time or too often either otherwise you might upset your stomach (too much stuff sloshing around) and your stomach can only drain so fast. It's not too hard to keep track of the timing either. Just glance down at your cyclometer and check.