So, I taped the living hell out of the hinge with heavy duty insulation tape. The kind of tape that is rubbery and sticky on one side and shiny, silver on the other.
This is what I get for not really addressing the problem - it still leaks.
If you're building a teardrop and reading this remember to cut your hatch hinge with a nice overhang on each side 1-1/2" or so should do it. Learn from my error.
Wish me luck.