Sewer Tote - 2 vs 4 wheel

Not much to add here. We have a thetford 35 gallon 4 wheel version. We got it that size because our gray tank was around 60 gallons or so in the TT we had. The class c has half the size gray tank (30 gallons). We have not had to use it with the class c yet, but it is nice that I can dump all the gray tank contents in one trip, rather than two. If space is not an issue of storing it while traveling (I.e. Truck bed), then I would go with one that's at least the size of your gray tank if it's under 35 gallons or so. The larger they are, the more you will want 4 wheels. Just remember that water weighs over 8lbs a gallon. So even a 10 gallon tote will weigh over 80 lbs. would you rather lift 80 lbs and drag it to your hitch or drag maybe 160 lbs (20 gallon tote) that's on 4 wheels. I will tell you that mine full weighs nearly 250 lbs. I've pulled it over gravel and uneven ground without much issue. If you aren't to able to lift or pull anything of some significant weight, keep that in mind.