I believe the cassette in our truck is similar to those used in many expediter trucks, regardless of sleeper brand. For those who don't know, a cassette is a device that connects to the toilet built into a truck or to a porta-pody that is carried inside the truck. It collects what the drivers use the toilet to get rid of.
For times when dump stations are unavailable I have a piece of luggage on wheels that is large enough to house the cassette. It is duffel bag on a wheeled frame with an extendable handle.
It works well when we need to tote the cassette into the shower to dump it into the toilet there. It draws no attention or negative feedback at all.
It came in especially handy once in California when we were in a high-rent area such that a four-star hotel would be looked down upon by everyone who frequented the five star hotels there.
Needing to dump the cassette, I waited until a quiet part of the night, put on my church clothes (blazer, polo shirt, khaki slacks) and strolled into the Hilton with my "baggage" in tow. I had the public bathroom to myself that time of night and was able to service the cassette with ease. The cassette was favorably impressed but I was careful to not repeat the routine lest the cassette get spoiled.
Some people down the cassette and say a full-fledged RV tank is better. I disagree. We are expediters, not RV'ers. We drive to and layover in places RV'ers don't even dream of. A cassette provides mobility and flexibility that a built-in tank cannot.