I did say that 40L could probably be 50L and then everything would fit comfortably inside. The z-rest does get beat up on the outside. The snowshoes probably will never end up in the pack, and the bottles hang in cozies on the outside - I don't like to stop for more than a minute or two, especially in winter.
I don't bother with rain pants - they are pretty worthless except for butt sliding. If I am moving, they only make me sweat and nylon pants are quick-drying. I do have two contractor garbage bags which provide as much as the pants in a survival situation. I can even squeeze a hardshell and a softshell in if I really want - the softshell generally provides most of the protection I am looking for. Hat/gloves/goretex mitten shells/extra shirt all fit in a stuff sack. Knife/whistle/first aid take up very little space. Clif Bars easily fill up the empty spaces between stuff sacks.
I am likely to get Gryffin a pack for winter so he can carry some liquid water and food for himself. He seems OK with eating snow in the absence of liquid water, although I know this can lower his core temp.
Maybe you can explain why you cannot fit everything in 22L? I know a lot of people who make do with 14L or thereabouts. To them, 22L is big. I know for certain I had more stuff than 95% of the other day hikers in the Grand Canyon / Bright Angel Trail last week. Only the backpackers had bigger packs. The Osprey Talon 22 was a very popular pack that day.
Tim
p.s. in three+ full winter rounds, I have been absolutely alone (no people, cars, or fresh tracks visible for the entire day) at most five times.