Get a dual cage for behind the seat and get one of those bottles that can serve as a holder for your tools etc.
Another possibility, there are single and dual possibilities for handebar mounted bottle holders.
Also, Nashbar has Zefal Magnum (32 ounce) and Camelback (1 liter) bottles.
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Slow Ride Cyclists of NEPA
People do not seem to realize that their opinion of the world is also a confession of character.
- Ralph Waldo Emerson