This could be worth a try, especially for a relatively warm-weather quilt. The cotton shell would be a bit heavier than you might like, but remember that there was a time when the best sleeping bags had shells of Egyptian cotton...the same material used in good quilts.
Most homemade backpacking quilts are baffled, which makes them much warmer. Many, if not most, quilts are sewn-through, so probably wouldn't be suitable for lower temperatures. The trick is deciding what "lower" means to you.