Gene, we have similar coaches and I have never had reason to suspect the aqua hot exhaust was leaking into the coach. Ours exits aft of the service bay door, so its a blank wall above where the exhaust is located, no windows or vents. Do you keep a nearby window open while running the Fantastic vents?
I also was concerned about AH exhaust being a nuisance to neighbors, but I really don't smell anything when I'm outside when the AH is running. Time to do an annual service on the AH maybe?