This is not my own idea (I think it came from a VAF poster) but here is my implementation of it. The first pic is a blurry photo of the plunger and spring thing from the top, the second is the same stuff from underneath, and the third is what it looks like in the plane. The idea is that swinging the lever to the left stop feeds left tank, swinging it to the right stop feeds right tank. To shut things off, you push down on either spring-loaded stop and turn the valve past it. Obviously they'll be labeled at some point.
