I'm revisiting this issue. No trouble, but it needs to be done. I'm going to measure the fuel temp as it comes from pump, and see what actual temp is in winter to see if I might get away with smaller overflow tank. I'm also curious if tank temperature reaches much above 100 in summer? I think I can tee into vent hose, and bend a hairpin upward to just below lip of filler for overflow tank inlet? If You all see any flaws in my reasoning, don't hesitate to tell my Wife, as she relishes pointing out my flaws!