We boondock 95% of our trips, so here are my oberservations:
With a family of 4 and good water discipline, we consume 10 gallons per day. Last trip was 5 days and we averaged less than 10gal/day.
Casette toilets use less water than convential toilets. Also, teach your kids to do their buisness in the woods if possible. It saves water and teaches them a useful skill.
Replace your stock group 34 battery with 2, 6V GC2 golf cart batteries. This roughly triples your battery capacity.
You didnt mention camper size, but big campers eat more power and propane, especially in the mountains with cool overnight temps. With our 16ft hardside, batteries will last 6 days and a 20lb propane will last 10+ days with overnight temps in the 40s. Adding 100-200 watts of solar will keep the batteries topped off indefinitely.
Capture you grey water and use it for putting out camp fires at night.
Practice filling your main tank from your portable containers before you leave the house. I found a weakness in the transfer method that caused considerable spillage.
If you must run a generator at night, only use an inverter style. Sound carries a long ways and we have had many inconsiderate neighbors run their POS HF gen all night for no reason. (Idiots also emptied their black tank onto the road when they pulled out. ) Avoid running your gen as much as possible. People boondock to avoid the habits of city campers and enjoy the peace and quiet.
Bring a great camera or telescope. The sky is amazing after 11pm. We lost count of the satelites we saw. Shooting star count was around 10 on one night alone.
Bring a shovel, water, bow saw and splitting ax for firewood. Most sites have ample downed trees. On group trips, we bring chain saws and spilt and stack enough wood that tbe next campers usually have firewood for a couple of nights.
Also on that note, be aware of dead/dying trees near tbe campers. In some areas of CO, it is not uncommon for beetle kill pines to fall in high wind. Seasoned vets consider chain saw mandatory in some regions to avoid getting trapped.
Bring a tow strap, chain, winch, etc. Heavy rains create big mud holes fast.
Bring excellent flash lights and lanterns, its dark in the woods.