And in one place I had an enlarged hole on the shop head side. I don't remember how I got it. But I made a two hole splice and it worked like a washer across the enlarged hole. I used longer rivets and I'm sure this is a good joint. Probably overkill.
You'll also notice I primed the whole bottom skin. I'm thinking this is where any condensation would eventually end up, so primer there is probably best well spent.