I didn't understand what you were after when you asked about metal windows in my thread the other day, but now with the additional explanation I get it.
Maybe something like the JK Safari Cab rear barn door frame could work. It's intended to be attached to the tailgate and the tailgate/barn door upper opens and closes as one piece, but it could also be attached to the factory hinges and swing up. When the parts come out of the mold, the window opening isn't cut out, so if a solid panel was the goal that would be fine.
Here's a photo of one of the barn door frames that's not completed yet, the window opening has been cut out but no glass installed.
I hesitated to even post this idea because the JK Safari Cab and/or the barn door isn't in production, but if it ever gets to production, maybe it would be a solution for you.
You said you planned to use it on an URSA Minor, here's a concept drawing I did some time ago showing the barn door installed on an USRA Minor (with the window installed, but it doesn't have to be). And this concept shows it configured as a barn door, but as I said it could be configured to swing up as a hatch.
Just some food for thought.