I've made a bit of a science out of efficient and fast dumping myself.
My sewer hose is stored in a fence post cover I installed at the sewer connection. It actually snaps in place.
Flip the lever and it ejects the hose with a 90 already on it.
(first hose keeps second hose secure in forward tube).
When it comes to dumping, I don't "rinse" with fresh water. If dumping 30~60 gallons of soapy grey water doesn't flush it good enough, nothing will.
I've also set up a way to flush the black without taking too much time (& if no one is behind me).
I have installed a third valve where the sewer hose attaches.
So I can dump the black, close this valve and let the grey and black equalize which forces 20~40 gallons of grey backwards into the black tank. This only takes takes 30 seconds or so.
Then I dump the black again (now with grey water in it) and I always get a lot more TP and "stuff" out.
Finally, I dump the last 20~30 gallons of grey which does a final "flush" of the sewer hose. Since the hose snaps into place, I don't even have to install a cover over it
We also have a hose-powered black tank flusher but I only use that at campsites.