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...
We use ours when we are camping where we do not have full hookups which is mostly in the National Parks for 7-9 day camping sessions. We have a 10 gallon tank (80 pounds when full) that my wife and I can either load into the back of the truck or just roll a fairly short distance to the rest room which has an outside sink. We have only used it for grey water. I would not camp without the tank unless we are going for just the weekend or have full hookups.