Teardrops n Tiny Travel Trailers

Does the long side go inboard or outboard?
Or to put it another way ...
Which is the sealing surface? The short one or the long one.

If you google "How to build a Galley Hatch/Lid for your Teardrop Trailer OregonTrailR " you find a very interesting video, and towards the end it may answer your question. Hope it helps.