Cumulus - Aerial 330

Well, “freely” overstates the benefits. It takes a slight effort when you turn to keep the uninsulated bottom of the bag pressed against the pad when you turn. I love the false back design — especially the part about having a -7C sleeping bag that only weighs 450g (!) — but there is a little bit of learning curve to turning without exposing your back side to the cold. There are no drafts, which is nice, but warmth is still prone to escape until you master that skill. Zenbivy’s system is designed to fix such problems: you can turn easily draft-free. I don’t like ZB though because of the extra weight and complication of adding a sheet. A wide quilt is simpler, easier to get in and out of, and mostly solves the draft problem. Also, maybe it’s me, but I’m not going into the backcountry to mimic sleeping in a bed at home.

The Aerial is not a quilt though. It's an absolute minimalist sleeping bag, quite narrow, but has an unfilled backside.

For the sleeping bag I’d recommend a zpacks, timmermade or cumulus 30f range sleeping bag you could push into much colder temps wearing alpha 120 bottoms, down jacket, and down foot booties inside the sleeping bag. I’ve used this combo of clothing to push my 12oz 50f sleeping quilt down to 20f comfortably. If you plan to camp mostly in the summer I’d get the 50f bag and just wear more clothes inside it to push temps lower in fall. I switched to this technique and was able to reduce my pack size a lot and half the weight of my sleeping bag and its bulk. It works well since I’m already taking the alpha pants and down jacket anyways so I might as well wear them and save weight on the sleeping bag. The wind makes the biggest difference to me for how much insulation I need at night. For High Wind below freezing a windproof bivy that can fit over your pad and quilt makes a huge difference to your overall warmth and stoping drafts. Many UL quilts with 7D fabric are not very windproof and even a 20f bag can feel very cold at 20f in high winds. I like to summit camp and it’s often very windy above 6000ft. For the sleeping pad I’d recommend the thermarest nxt https://cascadedesigns.com/products/neoair-xlite-nxt-sleeping-pad?srsltid=AfmBOop1YJvl8n8oPU1vCNvveJ5sopEYhuUIcb1ORgJmz5-Sc-vxRd-W If 6.1 and the wide thermarest fits me but is still small. It packs down very small and is the most comfortable and insulated pad for the weight that I’ve tried yet. I have slept at 10f in the snow and been fine with it. You can also pair it with a gossamer gear thin light foam pad and gain more R values for freezing temps.

Take a look at cumulus bags. They can do custom fill (up or down, “waterproof” different fabrics etc ) and custom sizing for it as well if you wish. Not cheap but personally I think they’re the best down bags on the market.