I have a venturi type vent stack device that draws the gases from the tanks and disperses that above the roof. The device always points into the wind as to take advantage of the slightest breeze. Going down the road, there never has been a problem with any odors in the cabin.
This device is attached to our single 2" vent stack pipe. This device requires you to cut the pipe down a little so that it fits in the manner shown. The RTV is original. The screw seen at the base fits into a collar on the inside of the vain that allows it to rotate.