Remove air admittance valve

The air admittance in our Phaeton is located behind the washer/dryer. I have replaced it with a new, more expensive valve but I still get a slight unpleasant odot emitted from there. I know the trap for the washing machine drain can possibly be losing its water when I travel but I don't think it is happening, because I have run the washer for a couple of minutes to make sure it gets water. I don't think it mattered. We are very careful with dishwashing and try to make sure no food particles get down the galley drain. I even added Cascade to a 1/4 tank of clean water and drove with it a couple of houre to clean tank walls.

What I am considering is drilling straight up through the roof and adding a standard roof vent to eliminate the air admittance valve. The should be no wirund in this area but that's no guarantee. Just wondering it anyone else has taken a similar step to eliminate the air admittance valve.