I agree multiple tanks with multiple outlets are a pain in the... However you need to consider your usage.
I hook my sewer hose to the front connection which takes care of main bath shower and toilet.
My 40 gallon black will last at least a week if not more without dumping.
My rear connection is for kitchen sink and rear 1/2 bath. For the most part the rear grey fills very slowly. It is 40 gallons and it takes a long time to fill it with just the kitchen and rear bath sink going into it.
I basically ignore my rear connection because the rear tanks will not fill up in a week. They may even last 2 weeks. Dishwashing and washing hands does not generate 40 gallons of grey water.
I simply monitor my front connection and dump grey as required. At the end of the trip I move the same hose and empty rear tanks. I have found its simpler and easier to just use one hose. There is no need to get out a second hose,wye connection and other fittings to dump resar tanks because for the most part they won't need to be dumped until the trip is over. At which point I just use the hose that is attached to the front connection that is already out.
After completely dumping front tanks I move hose to rear connection and dump rear tanks.
If I were set up for a month or more maybe I'd take a different approach but for a week or 2 one hose works fine.
In my case the tanks don't fill at the same rate so I don't set up additional hose and fittings to dump tanks that will not require dumping until the end of the trip. Both connections do not need/require a dedicated sewer hose. One hose can easily serve both connections in many cases.
I try to spend less on set up and breaking time and more time relaxing away from the rat race.
