I have a couple of planes setup like this. you pop three holes in the tank stopper one goes to your vent, second goes to your carb, IE has the clunk and the third is your fill line. The way I do it is I barely stick the fill tube in the tank so that the tubing do not get tangled together inside the tank. and the way I de-fuel is through the fill tube by putting the plane on its nose. Only the carb tube has the clunk.

Randy