I like the idea of a quilt for the lack of entanglement when moving around. But I sleep cold, live in MN, and am 6'6" tall. Even the longest off the shelf or custom quilts will likely result in cold feet.
Costco has some down blankets for about $20. I got one, folded it over, and sewed across the bottom and about a foot up the side to make a foot pocket. I added a buckle to match my quilt strap and use it inside the quilt. It adds about 10F to the warmth and weighs nothing. I do wish the blankets were a bit longer but it does help when it gets cold.
I need to rig something like this if I can ever find extra long down blankets. Ikea used to carry some decent versions but they were just a bit too short for something like this.
