Sea to Summit - Hamelin Synthetic Sleeping Bag

A good synthetic sleeping bag would weigh less than 1.5kg (say, Sea-to-Summit Hamelin), will allow quite a bit of movement inside, can be turned into a blanket when unzipped.

I have a disco 30, M44. I went camping in May (65°F low) and September (60°F low) and was too hot, had to unzip and use like a blanket. I also went further North in October (45°F low) and was comfortable. My daughter has a Sea to Summit (30°F) and she was cold. Liners are an option but a royal PITA if you have to pee at night. In hindsight, I'd have gotten a lightweight quilt for warmer months and a 15°F for her.

I have a sea to summit backpacking bag that’s 15° rated and once it’s in a stuff sack it’s incredibly small for a 15°. Coleman is basically bottom of the barrel, sleepover style, when it comes to sleeping bags, I’m surprised you aren’t freezing to death at night.

Quilts can get drafts, but then also sleeping bags compress and lose loft as you shift and expose the compressed side. About even in my experience. Sizing, quality of pad straps, or user error are all possibilities if you've had better luck with a bag over the quilt. Also, audio books with a sleep mask headset and ear plugs. Give a pillow a try as well. I use the better sea to summit version and it helped my sleep quality a lot.