Hi, I've got my GP Extra all framed up and am in the process of covering it.

As far as the canopy, I have added 1/4x1/4 "Rails" on top of the deck flush with the sides where the canopy meets it. This provides a much better gluing/screwing surface and gives the hatch some rigidity. IMO, the way that part of the plane is designed is rather poor...very very fragile (without the rails that I added).