Stink from new(ish) RV

To confuse you more, one last possibility. We had trouble with sewer (rotten eggy) smell which I believe came from the black water tank roof vent. It found its way in while driving through some combination of open and closed windows, cab air vent and, I think, was affected by wind direction and air pressure (not while driving with a 60 mph head wind but wafting in when driving slow, sitting at a light or in traffic etc). I actually never did figure it out for sure but by adjusting window openings, cab air vent supply on and off and often when just hitting the open road for an extended period it went away. I even put a slight extension on the roof vent to raise it up a little which seemed to help. Mysteries, Mysteries. Especially when it comes to smells. RVing can stink sometimes.