Cyclone vent install- mount to existing sewer cap collar?

Although I can't offer any direct advice to your question, I can tell you that for us, the Cyclone made all the difference. It was very stinky on even short highway trips (our usual stomping grounds are only 20 miles out). We recently went to a little farther one (100 miles) and with the wife's sensitive nose/stomach, decided to try it. Worked like a charm, didn't smell a darn thing.