My 27 hunter has a MSD style porti pottie which means it can be converted to a pump out style. I have the adaptor needed for the pottie, the hose and the deck pump out fitting. I also need to run an air line (1/2") from the built in holding tank to the outside. The question is... where should I run this air line to? High up on the side of the hull? What type of thru hull fitting should I use? Just a regualr drain like the bilge pump drain?