I installed a second water pump in the pass through near the fresh water input. output of the pump goes to fresh water inlet, inlet of the pump goes to a "dip tube"
then we bring along the 7.5 gallon blue water jugs. stick the dip tube in the vent hole, turn on the pump.
I have 40 gallons fresh, 64 gallons grey, 32 gallons black.
with the 40 gallons + 4 jugs (30 gallons) DW and I can easily go over 2 weeks at a few of our favorite boondocking sites.
Even with 2 grandkids, SIL, and Daughter we can go a week pretty easy.