A couple of comments....
We will only camp at full hookups because of the shower issue. A one night stay would be different, dump on the way out.
The navy shower thing never worked for us. The main problem was that when you close the shower head you setup a gravity loop and the hot water starts running down the cold circuit. When you turn it back on you are getting full hot water out of both sides and its HOT!. We just learned to shower quickly and leave the water running. Our current TT has electric over gas HW Heater. The recovery is very fast which of course means we can take longer showers because the makeup rate is stronger. We have only showered once each in it but had plenty of water. Next trip I'll take a longer shower to get a feel for just how long I can go. If we have to replace the HW heater at any point, I will go with one of the high temp units with a mixing valve. And a 10 gallon electric over gas if it will fit. I think that gives an effective 17-20 gallons of hot water? That's pushing a 10 minute shower.
We lived in a camper with a 6 gallon gas only for a few months. We got it down after a while. I would run the hot water till the burner lit. I would wait about a minute and start the shower before the burner went out. I sometimes had to trim the cold back towards the end of the shower if I went long.