I have the 32 gallon Barker tote. It's towed behind my truck at least a thousand miles over the last 17(ish) years. It's used every time we go camping, and I use it at home to dump my tanks into my septic tank.
I replaced the wheels about 5 years ago when the rubber literally separated from the plastic wheel. I got new wheels and it's been doing just fine ever since. The slide valve started leaking just last year. I called the Barker company and they sent me a new valve to install completely free, even though the tote is nearly 17 years old. They said it was under "warranty!" I was extremely impressed with that.
If I ever have to get another one, I'll switch to the 42 gallon version. My tanks, if dumped just right, I can dump successfully, flush my black tank and completely empty my black and grey (shower) tanks in the 32 gallon tote. So, I dump about every 2 days. My tanks are all 30 gallon, so if they are completely full, I'll never over spill the 32 gallon tote, but then, I can only do one tank at a time. So my process works well for me.
About moving that 32 gallon tote? I have no problem moving it by hand. At home, I use to tow it behind my John Deere riding mower to a ramp I built for my septic tank clean out. But I found I can simply pull the tote by hand, over the drive way, and over the grass with no problems at all. So I don't use the lawn mower any more. 32 OR 42 GALLONS SOUNDS LIKE A LOT, BUT ON WHEELS, IT'S NOT HARD TO MOVE AT ALL!
On sand, (Florida, South Carolina, and Virginia, I will tie a rope to the tote (when it's full) and pull it up to the road with my truck. Once on the road, it pulls easy by hand. This works great! It also works well using a rope IF the tote is down hill from the road and you've got to pull it uphill to get it attached to your truck-car to drag to the dump station. Remember this trick, you will need to do it sometime. But, that has happened only 1 time in 20 years of camping (on a hill) and about 4 or 5 times on sand (in 17 years of using the tote!)
Get the Barker. You are correct. The slide valve with the hose works very nice. And by the way.... IF you do it right ... you never have to use rubber gloves either!
Just learn when to shut the trailer valves off so it won't over fill. It only takes once to over fill, and then you learn it's limitations REAL fast!
Good luck!
Edit:
By the way. The first photo below, shows how most will tow the tote behind their vehicle. I had the handle pop off the hitch once and the tote decided to go 4-wheeling on it own. That was an embarrassing moment.
I tried different ways to secure the handle to the hitch ball, but eventually I started using these threaded D-rings. (Second photo). The tote has NEVER gone 4-wheeling again. THIS is the way to connect it, so it won't separate from the tow vehicle at the most embarrassing moment imaginable!