im not an experienced cold weather survivalist but have backpacked in sub freezing days with 12 degree nights. A thermarest neoair and 0 down bag kept me toasty, even under a tarp. Snacks, wool socks, and h20 should be good to go. IDK how waterproof a m65 is but a hi quality waterproof shell with vents is nice. Hiking though I sweat me arse off so mostly wear a light clothes while moving. If just a bag to keep in car jic I have to walk, I would focus on H20, socks, snaks, shell and mouse gun with 2 mags and 25 xtra rounds. ....and a decent headlight.