I've heard about using the blue tote for dumping so you don't have to move the rig. When the tote is not as large as the tanks you are dumping from do you just have to wing it and hope you shut it do...
I have a 25 gallon tote, and 30 gallon gray. I just wing it. I have not spilled it yet. Worse was loosing the hitch hoop and lifted the 25 gallon tote full into the back of a suburban. Walked it in so wheels went up first. Had it completely pointing down and rolled/lifted it up over the step bumper solo. I am 5"9 170lbs and it was a chore.