I carry a Camco 28 gallon tote on its side between the propane tanks and my tongue jack on my 2922KB. It's a tight fit, but the perfect place (for me) to store the large size waste tote.
I've towed around 10K miles in two years with the tote stored as it is. I have foam plumbing pipe insulation attached to the rack to cushion the tank.
I'm attaching photos of the test fit of the rack and a view of the tank when we're under tow.
The location is tight but doable for even the large tank I have. (I'm not aware of larger size tanks and the 28 gallon size just fits while wrapped in a protective tarp and smoker cover.)
Rich and Lynn
2021 2922KB