Mountain Hardwear - Phantom 15 (800-fill)

I don't feel like I have enough to say for a new comment so I'll respond to yours! I actually have the old red-blue version of this bag, but with 10D DWR fabric. I didn't know it was available with GoreTex, sounds wild. Where I am from this bag has been, and still is, one of the only options for a winter bag that is somewhat light and readily available. You're absolutely right about the narrowness, it looks to me that they kept it about the same between the old and the new model. I'm skinny and tall, so the narrow cut is amazing and probably the only bag ever to not have enough space for me twice over. And they are expensive, but I'm not sure if it's just a market thing. Anything warmer than that is already a rich man's toy (I'm not in the US). I got mine for a discount which made it somewhat worth it, but the temp ratings are still awkward: The Phantom's -11C/13f comfort means every trip is a damn gamble on weather you bake yourself or freeze your ass off... It's been most comfortable in temps where I could've used my true three season bag for about 1/3 of the weight and bulk.

My -8 mountain hardware bag is good enough for me in May. I would say if your packing in a cot by car just bring a couple extra blankets. If you get too cold just grab a blanket. Above or beneath your sleeping bag or both

Late to the Party, but the Mountain Hardwear Phantom bags are no longer a good value proposition (not to imply that they were before), but you can get a Western Mountaineering Kodiak MF (Microfiber) for $850 or the Storm Shield Version for $985. The Phantom Windstopper 0 degree starts at $1,100. Western Mountaineering is made in the US and so some of the tariff-related inflation is not hitting them as hard, making them a better value proposition. Not to mention Western Mountaineering makes the best down products in the world. Other folks have mentioned Gryphon Gear. Another awesome option. You may need to wait a while to get one though. Feathered friends is great too but I think Western Mountaineering is amazing. My recommendation, Get a Kodiak MF. The Microfiber fabric may look unassuming at first, but it is incredibly durable, tightly-woven fabric with excellent weather/water resistance and it breathes super well, critical for multi-day winter outings. I have a Puma Storm Shield and while I love the fabric and the fortress feel, a laminate fabric like that takes a long time to pack into a stuff sack. It just traps air like a balloon. The microfiber is a dream fabric. A proper microfiber fabric where the filament count is equal to or higher than the denier of the fabric.

For posterity, the sizing is indeed important.  The non goretex versions are "performance mummy cut" which mean these are smaller.  The goretex ones are the ones you bring for expeditions, these are the big bullet proof tankers known as "Expedition mummy cut".   Inside the Expedition Cut, you can gear up with your belay down jacket and stuff, theres more room and then you can get a -18c instead of a -40c for example. The beefier goretex expedition one is interesting if you sleep straight outside in winter, with no tent.  It stop wind and melting snow wont wet the sleeping bag.   For serious winter stuff you can add a VBL in that melting pot of kit to manage humidity and dew point but its not in the main subject. Things to remember: - Performance cut; - Expedition cut. I personally have the blue and red MHW -40c goretex, the -18c, the -18c goretex and the -9c. Each sleeping bag have its particular usage in my activities.

My current down mummy one from Mountain Hardwear that I got for a crazy deal (<$90). There are zippers on both sides and the toe area. I move a lot in my sleep, and the slightly wider area up top makes it easier. (It's wide enough for my arms to go to my shoulder area, even zipped up.) It's a huge step up from my previous one, a cheap synthetic mummy.

I have the Mountain Hardwear and love it. My kid has a North Face Inferno and loves it… and I worry less about water damage. I trust OutdoorGearLab.com for reviews. 

It's really a personal choice. I would suggest you try the MH sleeping bag. It's a free way to test a type of sleeping bag. Worst case, you buy another one later. I personally use down sleeping bags because they are lighter and compress better. But they are more expensive and take a lot longer to dry if it gets wet.

Mountain Hardware has a couple bags that are compatible, my wife and I use them. They are a little bulkier, but affordable. You could also look at something like the Zenbivy Double bed.