Elk hunting, I always have a 650 fill down jacket in my pack for emergencies, some kind of ear and face covering as well, along with my first aid and "possibles" kit. I seldom wear it, but when I hold still the down is very welcome. Pretty much otherwise all I wear is layers of wool, and they have served me well over decades. True, wool is not compactable, but that is why I have some pieces of paracord on the outside of my pack, and also my pack expands larger than I normally need so when I am climbing rapidly (especially in the early morning) I can shed layers to keep from getting really soaked. When I get to where I am sneaking again, I re-layer. An ensolite pad can work well, but I find myself sitting on my pack as the only available dry spot, and it gets me in a better sitting position for shooting should an opportunity crop up. But then I am not as flexible as I once was.
A couple other notes, although many packs say "waterproof" they never are, and pack covers can be less than effective and annoying. The simple expedient of a garbage bag inside your pack can keep that down and the rest of your gear dry even if you get a fall rain. A few contractor bags in the bottom of your pack can provide emergency shelter/rain poncho and a place to keep meat clean. Time tested.
And, when you go back to pack meat, don't leave your emergency gear in camp. Things can happen, weather can arrive, something may delay you until after dark, injury, etc.. It is a little extra weight to carry back and forth, but someone ought to have that even if you are "just packing meat".
