After my rant above, I did more research on the Waste Master the following day. Once I learned that it was originally designed to be permanently attached to the RV, things made more sense.
With some finagling, I'm able to stuff the nozzle back through the porthole in the bottom of the compartment so I won't have to disconnect the hose. I'll put a cap on the nozzle to prevent any drips from the end.
As for carrying an extension, I'm able to extend the Waste Master a full 20' from the rig. This is within a foot of using my two Valterra hoses. The Waste Master hose also stays in place without accordion-ing like regular sewer hoses.
I took the hose to an RV dump station and checked that it does fit into a standard outlet with the hinged metal cover. It's a bit snug getting it under the lid, but it does fit.
As for accessories (adapters, hoses, etc.), the best place to get those seems to be at the inventor's site, Drain Master – Welcome to Drain Master
He has all the available pieces and the prices are lower than Amazon.