We've taken our 22mle out a handful of times now and I'm feeling more confident hooking up, unhooking and dumping etc.

I follow the 2/3 black/grey suggestions for dumping and have found a good rhythm; I keep gloves on the drivers side cubby, hose with clear elbow on the drivers side to make things go quicker.

I have a couple questions not quickly covered by Googling.

I stand and watch the black tank drain, but once that finishes and I start the grey tank and the initial 10-20 seconds of water bursts out I head inside to dump a couple of gallons of water (and treatment) back into the black tank. Is it best to watch it the whole time?

How long should I let each tank trickle drain?

Is it okay to use to dump station potable spigot to flush the black tank? The only one I've seen so far had a back flow prevention adapter of sorts on it.