OK, so I built the hatch first, fit it on the camper and fit the hinge to the hatch. The 45” reference was just me showing off about how frugal I was with my materials. No actual math was used in the construction of my teardrop… hell, I barely had a plan!
I’d say just stand back and to see what looks right. It’s like a roof vent in that no matter where you put it, it will need to be sealed properly. And let the hinge overhang the sides a little to drop the water away from the hatch.
