Yes, that's it. We had our fresh water tank split and drop about 6" last summer but had two trips on the schedule before the dealer could get the tank ordered and installed. So we filled two Aquatainers and used a Y-connector hose to draw from the two containers simultaneously. Like this:
(the narrower Desert Patrol container was just there so that I could top up the Aquatainers).
I have friends with Jaycos and they have something similar to the Anderson valve with the notable exception that they can draw water from an external container to fill the on-board fresh water tank. It seems like a better solution. I bought a small pump from Harbor Freight but it adds to the messing around when you want to fill the fresh water tank. And if that pump fails, which mine did, then you've got a new challenge. I now carry two pumps.