I have 2 gas planes that I store in my basement and never have fumes from them. Here's what I do. When done flying, on one plane I drain the tank as best I can by flipping the plane over and sucking it out the vent, then I cap the vent line with a fuel dot. The fill line is also a fuel dot. Since the carb is closed and will only draw fuel if the engine it flipped over, I never have gas leaking. On my other gas plane it has a 32 ounce tank, and I put a clunk on the fill line as well as the feed line, so I can drain the tank all the way to empty, then plug the vent line on that one too, it also uses a fuel dot for the fill line. I also have a glow plane, and even if I drain the tank, I can still smell the fuel.