Okay, so, the first camera battery died today. One of my spares is broken, but I'll keep it out at night to let it dry in this dry, dry, "but it's a dry heat!" air, in hopes it'll be functional again. I won't try it until the end of the trip, though, in case it does something weird and ruins the camera.
I managed to get over 500 pictures on the first battery, I think close to 600, which includes turning the camera on and off, on and off over 200 times. I'm going to turn off the picture review, turn down the LCD brightness (which today I discovered was on full-bright), and try to minimize the on/off use as well as I can. I'm thinking of turning of the continuous autofocus, too. Not sure on that one.
Still, 600 pictures in 2 days. I'm both pleased and hopeful that 5 cards and 4.5 batteries will be sufficient.