This video is embedded in one of the threads linked above. Kind of a specific description of what is happening with the coupler as it goes about its day.
Cave Creek Canyon outside of Portal, AZ is one of our favorite spots. Beautiful area but there are some big Timber Rattlers in there too so be careful. And speaking of hot dogs, you haven’t tasted a good coney dog until you’ve had a Flint style coney made with Kogel’s Vienna franks. People ship this brand around the country they are so tasty! And yes, they taste awesome with mustard, onion, sweet relish and ketchup! Nummy!
On our 320 the low point with the trailer tipped forward would be under the passenger side bench near the door. Seems like it would be easy for the factory to put a fitting near that radiator that you could attach a hose and gravity drain out the door to a bucket. I'm going to investigate that possibility with a friend who's a bit handier than me. He's put quick disconnects on all types of motorsports equipment to flush and drain easier. Got to be a way.
My thoughts as well. I was tracing my T@b system today looking for a low point that, in conjunction with the boiler drain, could be used to gravity drain the whole system. Problem is, if you are under warranty and modify the system, I think you void the warranty. However, if that low point corresponds to a hose connection, that opens up other options.