We actually have three sewer drains, for four tanks. The rear half bath for the slide out bunk room, a galley tank for the mid kitchen and the forward bath room. So when parked, I use a Y to connect the front main tanks to the galley tank with short 5 ft hoses, then a longer one to the dump location. I keep a long hose connected to the rear sink-toilet. To dump, I change which hose is stuck in the dump inlet.
Yes it is a pain, but we use the fifth wheel only for longer stays. The truck camper goes most trips for short stays, when we are traveling, as it has only one sewer outlet. On the 5th wheel, I carry about 50 or 60 ft of sewer hoses and many connectors.