an alternative to putting a hole in the middle of the quilt is to simply add a snaps on one side of the quilt. Space the snap pieces about 20" apart, 10" on either side of the center of the quilt. Then you can snap the quilt around your neck to hold it there while working with your hands. When not working with your hands, just use them to pull the quilt around to the front of your bottom.
My own synthetic quilt design is at http://www.geocities.com/frhiking/sewing_quilt.htm.
BTW: Momementum is indeed a nice fabric, but it weight 1.1 oz/sqyd and not the 1.05 oz/sqyd that is advertised. I tested the fabric weight in numerous ways, so I am sure of this. Also, Climashield XP 5 oz weight 6.5 oz/sqyd. I was not so precise in my measurements of the Climashhield as the Momentum, since it is hard to cut insulation to very precise sizes, but I am absolutely sure the weight is at least 6 oz/sqyd. That being said, I am not dissatisfied with either of these materials, since they are at least as good as ripstop 1.1 and Polarguard 3D 3 oz (which I have previously tested as weighing almost exactly 3 oz/sqyd, as advertised).