JoAnn seems to be targeted to home sewists and crafters, not the outdoor crowd. Once I found some Thinsulate, but that seems to be no longer stocked. If weight truly is not an issue, you probably could use their offerings to make a summer quilt, but may do as well buying a pre-made quilted blanket on sale. Depending on the temperature range you anticipate, if you still want to make a quilt, consider using "lame" (lah-may) fabric which is metallized as your inside face. It should reflect some heat. It may feel a bit scratchy, so you may also want to wear some sort of PJs using this fabric.