There are a couple of ways that seem to work very well to seal the hinge line. You can get clear monocoat to seal the hinge line with and you won't even notice that it's there. I've also had good results just using clear packing tape, this is a little more visible but not really that noticeable on the bottom of the wing and stab. The tape does need to be changed about once a season because after a while the fuel will make the glue start to let loose but for something quick it works well.