Using RV portable tote tanks

I'd go with the Barker tote with the pneumatic tires. It has a popup indicator to tell you when it's getting full. I've hauled black and gray water many many times with no issues. And I use the regular sewer hose to connect to it. And you are correct - when full, disconnect from the camper and let gravity drain the hose contents into the tank. I do use gloves if the black tank needs drained - which is not often. I was fooled by the sensors when I was a newbie.