There is a lot of good feedback here already, but I can't resist adding my opinion to the lot. In the past I did a lot of overnight runs in the Sierras, the Olympic mountains, and the Cascades. I learned that radiant barriers are surprisingly effective (as Neoairs and the Blizzard Bag demonstrate).
I carried a 9oz MYOG down quilt with bonded seams and a 0.33 oz shell, and two mylar emergency bags. One mylar bag went inside the quilt, aluminized side out. The other bag went outside the quilt, aluminized side in. This reduces radiant heat emission where it is produced (in the warm inner layers), and what little is emitted is reflected inward at the outer layer.
I carried a light down parka, and I added snaps to the cuffs, hood, and hem. I added matching snaps to the outer surface of the quilt. When inside the quilt, I snapped my parka to the outside of the quilt, under the outer mylar bag. The air in there is dry and on the seven occasions that I used this setup I never found that anything in that space became damp. I also brought a pair of women's nylon stockings (fuzzy, winter weight). They weigh almost nothing (less than two ounces), and are fragile, but they are ridiculously warm. They will inevitably get a run in them when you use them outdoors, but you can just throw a new pair into your kit when you get home.
I also had a 0.51oz cuben poncho tarp (which I still have). I think the suggestions to use a bothy seem a bit silly when a large poncho tarp can be used as a poncho, a grounsheet, a tarp, or a bothy (with a drawstring hem).
I never carried any kind of sleeping pad, but I made nests from grass and debris that not only elevated me a bit from the ground but also provided plenty of insulation. The edges of the oversized mylar bag drape down over the nest, trapping a bubble of warm air beneath you.
I also always carried a firestarting kit, but I never used it. I have to disagree with those who advocate taking inadequate insulation and relying on fire. That's foolish. A good, lightweight, well thought-out insulation kit will never fail you, and it works even when it is wet and windy and you are immobile. You cannot always count on making a roaring fire. Even for the proudest bushcrafter, wet fuel, a sprained ankle, and a bad storm can make a good fire impossible.
For under two pounds (and 25-30oz if you pay for cuben), you can have a down quilt (from Tim Marshall, say), two mylar bags, a down parka, a pair of winter-weight nylon stockings, a poncho tarp, and a firestarting kit. This in the same weight range as the options you proposed in your original post, but it will keep you much warmer and drier.
