One advantage of sliding the open end of a zippered, or zipperless, sweatshirt up over the outside end of the sleeping bag is that it still gives your feet some wiggle room and provides an extra layer. If packing light, it might mean I've sacrificed using my sweatshirt as a pillow, but it works nice in the middle of the night when the temp. drops unexpectedly, cold feet won't let me sleep, and I am wearing most everything else.
Liked the idea of the Y-stick - simple ideas that make it nicer to be outside. Thanks!