I might add one more thing ... get the biggest tote you can afford. Many folks don't. They say they get too heavy, and yes they do if you try to lift them. On wheels, a 32 gallon and a 42 gallon doesn't make much difference.
If you are on sand or loose dirt, you can always attach a rope to the tote and tie the other end to the bumper of your truck and pull it up to the campground road. A 2 wheeled version, you'll have to not only lift one end, but you'll also have drag it by hand through that same loose sand or dirt, and that's almost impossible sometimes. 4 wheels is easier in my opinion.
Why the largest you can afford? Because if your tanks are 50 gallon and your tote is 30 gallon and the tanks are full, it's very, very easy to over fill the tote. Now you have black water in the dump hose caught between the tote and your camper. You know where that goes once you disconnect the hose? yep... all over your shoes and the ground.
Even if your tanks are smaller, if the holding tank on the camper is bigger in capacity than the tote capacity, you run the risk of over spilling, and that just ain't pretty!
If your tote is bigger than your tanks, you will never overfill.
My current camper has 30 gallon holding tanks, my Barker is 32 gallons. As long as I dump one tank at a time, I'll never spill on the ground with an overflow.
I dump mine every day. Black first, then the shower grey, which I always back flow into the black tank to rinse it better, and if I do this every day, it never overfills the tote. My third tank is the kitchen galley. It's also 30 gallons, but during Summer camping, it may take 2 weeks to actually fill it as we do dishes and cooking outside and wash them outside.
Edit:
About the height and actually attaching to the hitch of your tow vehicle to transport it to the dump station.
Below are a few photos of mine. The first photo is NOT the good way to do it. I have had the handle pop off the hitch ball and the tote end up in the ditch. So, the second photo shows how I over came that, and it's NEVER separated from the hitch again. The third photo shows how I transport it in my truck. It really is not very tall, and empty, not heavy at all. It affords stuff to be stacked on top of it when I need to (in the bed of the truck).


You can see the tote at the front the truck bed.
