This thread is progressing quite well, very much on schedule...
And we've even generated a new rule that we need to equalize our tanks, I can't wait for someone who asks if it's ok for them to NOT to equalize their tanks.
"Equalize" is not the goal...it's just the best you are going to be able to do if the gray tank is full and the black tank is not.
I guess some sort of fancy, overflow-with-backflow-protection system that automatically dumps extra gray water into the black tank would be slick...
I suppose you could drain gray water to a bucket and then dump it in the toilet...and I've read where other folks dump dish tubs into the toilet and bathroom sinks that go to the black tank.
..Or get a $15 twist-on valve if you are occasionally in an extended situation with plenty of water, but no sewer nor campground shower, no tote/dump station...You can get some extra gray water capacity by allowing the gray water to back-flow into the black tank (which normally fills at a much slower rate).