Rear Seat Dlete

The only "rear seat delete" I'm aware of was in the '68 S/S cars. they simply had carpet up to the cardboard divider , then had the cardboard installed.
In my old '69 Dart race car, we simply took out the rear seat, replaced the cardboard with a metal bulkhead per NHRA rules, and carpeted the floor and bulkhead. Looked good and clean. You can haul a lot of groceries in that area if you're just running on the street.