Yikes! Well, like most animal including humans, ball pythons can go much longer without food then without water.

If she is particularly picky, I would see if she would take a live african soft furred rat. I know you don't like the idea of live but sometimes that is what they need to keep them on a regular feeding schedule. See if you can find an asf breeder near you. Picky ball pythons will more often then not take an asf regularly. Plus, gerbils can get expensive. Asfs are also a natural food source for ball pythons.