Wayne,
I spent some time yesterday looking at different types and styles of car trunk hinges.
The style that I liked the best that seemed like they would adapt well to a teardrop application came off of an older Mustang.
The pivot point base would mount to the side wall rather than the roof.
I decided to build my own, but I'm going to design mine from the Mustang style that I looked at.
A concealed hinge like this will still allow for an easy method to seal the hatch.
I'll be doing a double seal with recessed gutter area like you see on most automotive trunk systems.
Here's a crude illustration of the hinge setup that shows where the pivot point is and how the "hoop" and hatch clear the roof line.
