We have a single round sink.
For dishes, we use a round plastic bowl purchased at Walmart in the outdoor summer items. We have a sort of dark red, looks nice with the interior. A dishpan is critical to not quickly filling the grey tank, IMO.
We use a soap/wand or a little hot water with dish soap in it, depending on what is being washed. Rinse and place on a drain mat on the counter.
In all likelihood, one uses less water with a single sink than with a double.
Most dishwater goes down the toilet, to keep everything loose and moving freely in there.
.
Maggie