Cumulus - Quilt 450

Take a look at Rab neutrino 400, or consider cumulus quilt 450 with some sort of down hood and/or down/climashield apex socks. Thermarest xtherm pad is great.

I use a cumulus quilt. Can be zipped up into a sleeping bag & you can sinch the ends up to however you like it!

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.