The photos of the CMC subframe are from cars that have burned (most likely). The subframe is what the door hinges mount to as well as the front hood hinges. I know some CMC came with the subframe not riveted/bonded to the fiberglass body - but they did get the subframe. My kit was called a deluxe - and that included the subframe attached as well as the doors hung (but not the door handles). You can separately buy the subframe and fiberglass body from Rusty Tubs but suspect that is because they sell mostly replacement panels and don't specialize in single entire kits.
For a car that had operational doors, the VW pan would be far too flexible. Open both doors and like an old rusty OEM 356 Cab, it would fold in half! Dune buggies on 14" shortened VW pans don't seem to have subframes but then they don't seem to have doors either.