If I’m going to be somewhere long enough to need to empty the grey tank before I’m ready to leave, I bring along a couple five gallon plastic buckets with lids, I use a sewer cap with the garden hose hookup and a quarter turn shutoff valve to meter the flow. I decant about ten gallons into the two buckets, put the lid on and put them in our tow vehicle and take them to the dump station and pour them down the drain. A couple trips and I’m setup again. It’s just part of camping for me. I like doing little camp chores so my day goes smoother and in this case I don’t end up with grey water in the shower floor pan. YMMV
I’ve never hitched up, dumped and went back for the same site in ten years of Escape
Camping. Carrying two fives over to the tow vehicle is my equivalent of a gym membership with no monthly fee.
Iowa Dave