Can I Get Some Air?

One of the things I've noticed about the sink in the Caboose is that it drains very s-l-o-w-l-y. In looking at the plumbing, it is obvious that there is no vent stack, which as any plumber will tell you, is vital for proper draining. I decided to experiment with this five-dollar fix from the irrigation section of my local Lowes. On the next trip, I'll attach this to the bottom of the Caboose, where the gray water drains. The vinyl tubing will be threaded outside and above the height of the sink. My fear is that this will be too low in the flow to have any effect on the drain, and so I may have to find the way to install this closer to the sink. The problem there will be the folding galley. I don't want to create a situation where the water reverses and flows out of the vent.