Must have at least One Wool blanket. These have a multitude of uses. Extra warmth on that guard detail. Bringing with you out on an LP/OP instead of your sleeping bag for warmth/sleeping. Or you can slip it into your sleeping bag for EXTRA warmth on really cold nights. It can be strung up in survival situations as a shelter. The uses are MANY.
-NVA blankets can be picked up for 15-20 dollars apiece
-Or any dark colored (not-obviously NATO) blanket is acceptable.