SOSS hines FTW! I use those all the time.
You'd need something that's going to hold a lot more weight. Even with an outside hinge you'd need a way to stop it at a certain spot so your door doesn't just smash into the side of the car when you open it, and it wouldn't be a very solid door. The element is already missing a lot of frame construction with the doors closing into each other. After you did that, you'd need something like the front door sliding hinge that ducks back into the body when fully closed, then you'd probably have to move the rear axle further back so that the slider goes all the way into the body when fully closed and doesn't crash into the springs.
I'd say the fabrication isn't worth the results.