I'm still out in Glamis, I think it's been about 12 days now, I can't remember.

I'm just over 2/3 on the grey tank, under 2/3 on the black, over 1/3 on fresh water.
The secrets are:
1. use paper plates and plastic ware, wash as few dishes as possible.
2. Use full face helmets and/or head socks to keep sand out of your face/hair, this way you can stay cleaner and take a real shower every other day. On the other days, you can do a sponge bath.
3. Teach everyone how to conserve water in the shower, there's an on/off valve on the shower head.
4. Turn off the water while brushing teeth, just rinse your mouth and brush at the end.
5. When washing hands, run the water at medium, you don't need full blast.
6. I installed a 3rd waste valve near the cap. If I fill up the grey tank early, I can open the grey valve, open the black, and excess grey will flow into the black, just like transferring with a bucket, only easier and with no smell. I only do this when the grey tank is full and the black is less than 2/3rds.
Between that, and solar panels, lotsa batteries, inverter, etc, I can stay out here up to the 14 day max easily, only using a 1/2 gal of gas per day in the genny.
I have 120 gal of fresh, and 50 gal of grey and black, ea. I often wondered where that other 20 gal of fresh water was supposed to go, but now I know. My dogs drink about 1 gal ea per day.