Would it be a bad idea to replace the sewer clean-out plug with a studor vent? I have seen some caps that look like the have a small grill. My guess it that might smell. So I thought why not put an AAV on that pipe? It seems like that would get more air in the system and help the flow. I have seen studor vents for septic clean-out. Just curious if that would work on a sewer cap.