Some fifth wheels and a few motor homes are unable to plumb the two toilets into one tank due to obstructions by the frame and other components. Consequently, they require two tanks.
My coach has the bath and a half that dumps into one tank. I use a SaniCon system, which is a macerator pump. I NEVER have to remove the sewer hose or rinse it out. I pump out my black tank and then my grey tank. Once its empty, I cap the 1" hose with a screw on cap and place it back in the water bay. I'm done. Many say its slower, but I'm not pulling out, rinsing and putting away nasty hoses. Mine also has an electric black tank valve with a second switch for the valve and SaniCon inside the coach. On the day of departure, I can dump my tanks before I even go outside. When I do leave, I put the SaniCon hose in the bay, roll up the water hose and roll up the power cord....about 5 minutes.