I don't know how I missed this before.
https://ck5.com/forums/builds/my-bob...ack-build.324/
Apparently I would not be the first to build a hatchback Suburban.
If I followed this path, I would (potentially) not narrow the rear, cut off the rear cargo area window and above, convert to a tailgate, create mating weatherstripped surfaces to seal, build a hatch, install lexan windows, and install a legitimate roll cage.