A lot of this is dependent on your climbing design. Is it reasonable for you to replace motors with pneumatics in the set up that you have designed? If it isn't then i think you've answered that question.
While looking at the battery to help you know if we think it'll make it through the match we'd need to know what motors you plan on using for climbing and how to use them.
It is also possible for you to charge up your pneumatics before the match with one battery and use a different one during the match.
As long as all other rules are followed, refer to this thread discussing pre-filling compressors.
http://www.chiefdelphi.com/forums/sh...hreadid=112532