I bet you could rig up a convenient outrigger (hang on her belt, or place it in a fanny pack) with high capacity NiCads or NiMhs in something from Sub-C to D size that would go for a couple of days. Or maybe even a small sealed lead-acid gelcell pack. No?
Yes, but, she would have to LUG this additional weight along with her! (She *could* wind up looking like an ENG (electronic news gatherer) cameraman/woman with a 'batter belt' around her waist).
The AA NiMH cells work pretty well ... when she was first equipped with this device the standard NiCd cells that it was equipped with were just shy of giving service throughout a waking-day ...