I wouldn't want that cyclone vent standing up so high so as to get snagged on branches. That can ruin a roof area if hit.
Here Is Your Problem.....
I think your problem is from the rv builder who usually drills too big of holes for the size vent pipe thru the roof. It gets covered up by the vent cover so you have to pull the vent covers to look down inside and you can see the problem. The sewer smell gas has access to GET down inside the cabin because it isn't sealed around the pipe to the roof down inside there. The covers cover this problem up very nicely so you have to pull the caps to see down in there.
