How to correct bow back in hatch on a finished trailer ?

Just got my first teardrop! Somebody else did a lot of great and hard work on this DIY build but there are some areas that need attention to make it rain worthy.
I believe the hatch is suffering from "bow back" where the seams meshing it and the side walls don't meet evenly and it leaks. I have some thoughts on how I can fix this but would love to hear anybody's experience, thoughts, or experiments.
Main Issue: Hatch Leaks at seam from bow-back
Suspicions:
I'm sure there's a lot of ways to describe "bow back" but what I'm referring to is the hatch not staying true to it's original shape after the plywood skin is affixed to the ribs. I suppose the ribs were not strong enough to resist the pressure of the plywood wanting to straighten back out out and it deformed from the the intended radius to one that's slightly larger. The result is... If it's hinged at the top, like I am, the seals along the sides become looser and looser as I follow them towards the ground. In my case the the seals are not touching by about an inch by the time I get to the bottom. Somebody has already attempted to correct the leak by doubling up the gasket at the bottom and sticking small wooden stubs under the gasket at the top. Neither of these things are working.
I imagine correcting this by adding eyelets to the top and bottom of the hatch and then connecting them with wire and a turnbuckle. I can then tighten the turnbuckle until the hatch bends back to the tighter shape I want. At this point I can affix additional, external ribs to the inside of the hatch to make it more rigid OR ??? Anybody's experience, thoughts, or experiments appreciated!
I also need to address the hinge itself. I feel like it doesn't extend far enough to the edge of the trailer so when it diverts water from the roof, it dumps it all directly at the seam. I have to research this next but if anybody wants to drop some experience here it would be much appreciated. Do hinges typically extend out further?
I made a quick web page to show the images of the trailer and the problems I'm working on:
http://www.rootsandshootsnursery.com/teardrop.html
I believe the hatch is suffering from "bow back" where the seams meshing it and the side walls don't meet evenly and it leaks. I have some thoughts on how I can fix this but would love to hear anybody's experience, thoughts, or experiments.
Main Issue: Hatch Leaks at seam from bow-back
Suspicions:
I'm sure there's a lot of ways to describe "bow back" but what I'm referring to is the hatch not staying true to it's original shape after the plywood skin is affixed to the ribs. I suppose the ribs were not strong enough to resist the pressure of the plywood wanting to straighten back out out and it deformed from the the intended radius to one that's slightly larger. The result is... If it's hinged at the top, like I am, the seals along the sides become looser and looser as I follow them towards the ground. In my case the the seals are not touching by about an inch by the time I get to the bottom. Somebody has already attempted to correct the leak by doubling up the gasket at the bottom and sticking small wooden stubs under the gasket at the top. Neither of these things are working.
I imagine correcting this by adding eyelets to the top and bottom of the hatch and then connecting them with wire and a turnbuckle. I can then tighten the turnbuckle until the hatch bends back to the tighter shape I want. At this point I can affix additional, external ribs to the inside of the hatch to make it more rigid OR ??? Anybody's experience, thoughts, or experiments appreciated!
I also need to address the hinge itself. I feel like it doesn't extend far enough to the edge of the trailer so when it diverts water from the roof, it dumps it all directly at the seam. I have to research this next but if anybody wants to drop some experience here it would be much appreciated. Do hinges typically extend out further?
I made a quick web page to show the images of the trailer and the problems I'm working on:
http://www.rootsandshootsnursery.com/teardrop.html