One thing nobody has mentioned, and I can't find in the specs, if this rig has a black tank flush. If so, then it makes more sense to leave the grey tank open, if you want to. For me, I hook up my hose, turn the flush on for about a minute (if not real full), then dump the black, while leaving the flush running. When it's done, I close the valve and leave the flush running for about 5 minutes, maybe longer (have 45 gal capacity), then dump again, then repeat. Use the grey water afterwards to rinse the hose. If you =don't= have a built-in black tank flush, then it might be smart to get, or make, a wand that you use to do the same thing, but from the toilet. Just need to be d@mn careful when you do this, though. :o
Lyle