I watched this
video recently on fitting windshields. The author kind of used your idea of fitting the windshield from posts to post then adding on the upper section. I experienced the same issue he had where you can make a perfect template but the PETG just doesn't bend like the template material. I used SeeTemp on the last windshield I fitted and held the upper portion with #0 screws. Like so many things in this SeeTemp is no longer available, I learned last week that Robart has ceased making landing gear products, guess I will need to make my own struts in the future.
At any rate the problem becomes that you need to use a thinner PETG to make the tight bend in the upper corners that the flat front area is weak, I would not eliminate the center post. The Cessna windshield below flapped from the prop blast but plane only lasted on flight due to a knock off Deans connector.
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