At least as of today I can tell you that the rear window can be removed after the Proseal has cured. I used Loctite on the screws as per rev. 0 after reading rev. 1 and forgetting that Loctite was a mistake and updated. Dang memory or rather lack thereof .
I had done a half decent job with the Proseal , but I get another shot at improving. I will mask off a larger area both on the acrylic and alum. so I can try and force a larger amount in-between the alum. and acrylic and hopefully have a completely filled seal. I had a few air spots on my first try.