I actually take a pillow case and a small inflatable pillow. In the past I have found my impromptu pillows made of wadded up socks, accidental pine cones, my burr covered hoodie, and yesterdays underwear to be un-sleepable.
Portable aqua water purifying tablets in my survival kit and a steri pen. Tablets Taste bad but they’ll allow you to get a drink when you run out of water, without trashing your GI tract for the next five years.
Pair of sturdy Rubber gloves and double handful of paper towels in my kill kit.
If your rifle is mag fed, carry a spare full mag in your pocket. I’ve only needed it once in 30+ years of hunting, but when you need it, you need it NOW.
Three ways to start a fire. Practice with them in crap conditions. LIke the spare clip you may never need them, but when you do they better work or ur gonna die.