Get some lipo's. Thunder Power 1320's weigh a little less than the stock battery and are lasting a little more than twice as long. I also have a 1100mAh PolyQuest battery that I use in the Axe, and by the time I'm done with all three batteries, my nerves are shot and it's time for a break anyway.
For field charging, I keep a small, lead-acid lawn tractor/atv/motorcycle battery. It'll charge about 20 batteries before it needs recharging itself.