
NEMO
Disco 15 Series
Spacious for side sleepers; bulky, temp rating optimistic.

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Splurge? 6 years ago, 2 EE convertible quilts. One xl/xw Apex 30° and a 950 down 10°. - my Best. Investment. Ever.- They work independently or together as quilts or sleeping bags... Can be zipped together to make one giant 2p sleeping bag. The Apex is an xl and the down bag will fit inside of it, added a liner for full 4 season in most of North America. Basically have 7 different systems with these two pieces. All together for around 4 lbs.
Splurge? 6 years ago, 2 EE convertible quilts. One xl/xw Apex 30° and a 950 down 10°. - my Best. Investment. Ever.- They work independently or together as quilts or sleeping bags... Can be zipped together to make one giant 2p sleeping bag. The Apex is an xl and the down bag will fit inside of it, added a liner for full 4 season in most of North America. Basically have 7 different systems with these two pieces. All together for around 4 lbs.
Enlightened Equipment can suck my entire asshole.
[EE are racist/fascist](https://www.reddit.com/r/Ultralight/s/afJAagvKix). It’s worth noting that they promised to course correct but I just checked and one of the posts that they were specifically called out on (with screenshots) for interacting with racists is still up. That aside, the convert is probably the worst quilt you can get. For one, the baffles are super long, which will promote down migration and cold spots. It does not have differential cut, which boosts performance and down stability (and at almost $700, should come as standard). EE products are also limit rated, so you better go at least 10° colder. A 0°F Convert, x-short regular is 800g and $670, which becomes 880g and $720 if you throw in a hood. A short WM Versalite is lighter (850g) only $35 more ($755) and is considered among the best bags you can buy. There is absolutely no reason to even consider EE.
Try Enlightened Equipment. The Conundrum and Convert come in a x-wide 70" shoulder girth and extends down a ways toward the hips at that width. Conundrum has a 3/4 length zip and Convert has a full zip opens like a blanket. You can order them in 10, 0 and -10F warmth ratings. You would need to add a hood because neither one has a hood. Another possibility is Western Mountaineering Cloudlite, although it is a 15 degree rated bag. It has a 65" shoulder and 68" hip girth. Conundrum and Convert can be used a quilt unzipped and might work if you can learn to stay warm using a quilt.
I also move around a lot when I sleep and found a quilt to work much better for me. I use an Enlightened Equipment Convert. It looks like it is a bit above your budget, though. I agree with u/Trogar1 that a good sleeping pad can make a world of difference. If you run cold, you could look at insulated pad and I would recommend an inflatable pad if you are a side sleeper. I found the extra few inches of thickness really help keep my hips from getting sore/cold vs. a thinner pad.
I bought a used quilt on marketplace. Enlightened Equipment 40 degree.
I’m taking my Enlightened Equipment quilt, 10F and weighs less than 1.5 pounds (think I’ve done that conversion right). Best thing I’ve ever bought! Also on sale at the moment with Black Friday - highly recommend

NEMO
Disco 15 Series
Spacious for side sleepers; bulky, temp rating optimistic.
Hammock Gear
Classic Burrow 20°F
Budget king; very warm but heavier than ultralight.

NEMO
Disco 30
Spoon shape for side sleepers; prone to zipper issues.

Western Mountaineering
VersaLite
Durable, very warm; premium price, too hot in summer.

Katabatic Gear
Alsek 22°F Quilt
Versatile 3-season quilt; secure pad attachment, high price.

Ranked #1
NEMO - Disco 15 Series

Ranked #1
Kelty - Tru.Comfort Doublewide 20
Ranked #1
Enlightened Equipment - Revelation APEX

Ranked #1
NEMO - Disco 15 Series

Ranked #1
Feathered Friends - Egret UL 20/30

Ranked #1
NEMO - Disco 15 Series