" have a Nunatak arc specialist with a little down removed to rate it around 40 degrees. How far can you push a quilt like that? Using long johns, hiking clothes, rain jacket, beenie and 1/4 inch thinlight from GG under a neo air? "
So essentially we've got a 40F quilt on top, about R 3.5 underneath and then long johns, basic hiking pants/shirt (doesn't add much), rain jacket (doesn't add that much except a slight VPL affect) and beanie (helps). I would guess maybe 30F with all of this on. You're missing any sort of real insulating layers. Aren't you taking any sort of a down, synthetic or fleece jacket?