I thought about this too, bought a REI Halo women's 10 degree long 6' bag (mens 0). The womens bag has a little more girth, it was on clearance at REI, 3 pounds, I am 5'8", 155 pounds, there is room to roll over in the bag.
Have only slept in it one night so far, had a 48 oz Nalgene bottle between feet, socks, trail runners, stove canister in stuff sack between knees, surprisingly it was fine, the overshoes would be fine along hips but I put mine under bag, on top of pad. I left my down booties outside of bag, there is room to wear them in it though or put along hips.
If your bag is tight, you might need the length, if roomy, then 6' is fine.
I buried my other Nalgene bottle upside down, in the snow, in my shelter, didn't freeze at all.
That was first winter trip, it snowed all day long, beautiful, best trip ever.