Here's the body style Suburban I'm talking about:

This is the one we used to have, just scrapped it a couple weeks back. It spun a bearing in the old 6.2, and then the guy who was going to buy it found a rust hole and backed out.
My basic intention would be to cut maybe three or four inches below the glass, and then blend that into a lower section made up from bed side panels, provided the angles of the windows can be replicated in the doors.
If the angles are funky, I'll use the roof and D pillar sections, rear doors, and make up blank sides. Custom windows would be needed, and then I could make them any angle needed to match the existing angles.
I do like the idea of lower barn doors and upper gate, but I'm not sure about fabbing up something like that. I'd probably end up using Excursion pieces, provided the width and height were close enough to work with. I do like the thought of not having a giant line up the rear view.

On edit: The Excursion has too much of an angle to the sides, I'll need something with more vertical sides.