You are right, you don't have enough clothing to be comfortable around camp, or stopping for lunch, or walking out in really severe weather. Also, if you are wearing all that, you will likely get wet from exertion, and it sounds like you don't have any dry clothing to change into when you stop hiking.

I'm a firm believer in lightweight hiking, but not at the expense of killing myself <grin>. So for winter hiking, I take layers that can be used together or separately, in various combinations depending on the weather. In addition, I carry separate layers for camp and sleeping.

I like a four-layer system: base layer, light windshirt, insulation layer, hard shell layer. For a winter hike, that would be a light wool long sleeve shirt, a Marmot Driclime wind shirt, a down jacket, and a waterproof/breathable shell jacket. Under normal conditions, I hike in the base layer and the wind shirt. If it's sunny and warm-ish, just the base layer. Raining or snowing, or just really cold and windy, add the hard shell. (This is *very* similar to your system, so far.) The down jacket is for breaks and camp, not for hiking, of course. This is the crucial piece for a winter hike, IMO. A good down jacket (and a good hat) means I can sit around and enjoy dinner, write in my journal, and otherwise hang out in camp, and be pretty comfortable down into the teens. I find this more suitable, for me, than climbing in my sleeping bag as soon as I stop hiking. The down jacket serves double duty, adding much warmth to my sleeping bag when draped over my torso inside the bag. Thus I can get away with a slightly lighter bag.

In my pack I carry Powerstretch fleece tights and a microfleece zip tee. These have several duties: first, they are dry and warm when I change out of my wet hiking clothes. Second, they add quite a bit of warmth to my sleep system. Finally, in very bad weather conditions, I can use them as warmer clothes to wear for the hike out. (But that negates their primary purpose, so this needs to be seen as an emergency only option.)

Sure, this is hardly "ultralight." And it's way more than I carry in warmer weather. But the weather in the Southern US mountains is somewhat unpredictable and localized, and I'd prefer to come home with all my parts attached.

EDIT: you asked for recommendations, so here are a couple: 1) A mid-weight insulated jacket like the Montbell Alpine Light Parka (with hood) or the Patagonia Micro Puff Hooded Parka. This amount of insulation will keep me warm down to 20 or so. 2) carry some dry clothing.