"Skip the pad entirely?!?! Surley you jest : ). Just for clarification, I would be considering this type of setup for summer/ warm weather only."
Yes. Torso pads are mostly for the warm days of late spring, summer and early fall. I use a NiteLite, 3/4 lenghth pad when I know I will be out in the woods on a fairly dry weekend, 2-3 nights. I use my pack over some kicked up forest litter to make my bed full length. This year, it has mostly been wet, though. I don't use a ground cloth, so I bring the NeoAir. The 13oz makes a nice bed...nearly as comfortable as at home. The NiteLite often is used to level the sleeping area.
The Nunatak Luna pad is the closest I can buy today. I slice this up with an electric knife. Then tape the sections back together, "fanfold," nesting the bumps. This makes a good pad, and a pack frame, for about 10oz. Overall, it is about 51-52" long. It is about 2.5" thick when folded, and will support ~25-30 pounds in the packs pad holders. The one I use is about 2" thick, from being squashed for a few years... Several people make packs with pad holders these days, but Gossamer Gear makes them a signature. You do NOT need extra stiffeners/internal frames, etc. It works quite a bit better than the Klymit AirBeam, too. But you have to allow an extra 3-4 inches on the hip belt till the pad becomes "trained." This can take a year or two.
The Z-Lite does not work as well. Nor does a plain 1/2" blue foam pad. The entire pack system weighs about 21oz including the pack and pad. A 25oz sleeping bag and a 14oz tarp round out the camp/sleep/haul system.