We have a Thetford SmartTote 27 gallon. I strongly recommend the Barker line of totes with the actual slide valve on the side.
Not sure I would want a Camco product for a sewer tote, but I haven't looked at their offering. In general, I find Camco products to be of the lower end quality of RV accessories.
My tanks are all three 37 gallon. It takes me three trips to the dump station to empty the black and gray tanks. I put about 1/2 black and 1/2 gray into the tote each time.
I don't think a level gauge will be much use. Anything inside a tank with sewage is going to get gunked up no matter how much you try to keep it clean.
We are full-timers, most of the time in campgrounds with sewer, or stays short enough so I don't have to use the tote. Once or twice a year max. But I carry it everywhere on a rack on the back of the trailer. Because if I don't have it, I've learned I will need it. With opposing slides, taking the TT to the dump station is a major two or three hour task.
Full-Time 2014 - ????
โNot all who wander are lost.โ
"You were supposed to turn back at the last street."
2012 Ram 2500 Mega Cab
2014 Flagstaff 832IKBS TT