I would simply take my ultralight hiking pack and its contents. I make a lot of my own gear, but you can buy similar items.
Pack: 1050 cu in silnylon 4.4 oz
1. foam pad 15x30 inches 4.0 oz
2. down quilt/sleeping bag, good down to 30F 17 oz
3. silnylon tarp 10.7 oz
4. 8 aluminum gutter nails, cut to 6" and sharpened 4.4 oz
5. plastic ground cloth 3 oz
6. aluminum pot 2.3 oz
7. platypus 2.4 liter water carrier 1.3 oz
8. propore O2 rain jacket 5.5 oz
9. fleece hat 1.2 oz
10. EMS down sweater 11.1 oz
11. Utility bag containing first aid, bic lighter, matches, birthday candles, DEET, small Swiss army knife, Campmor whistle/compass/LED light/thermometer, iodine tablets, soap, toilet paper, 12 oz.
TOTAL: 76.9 oz (4 lb 12.9 oz)
12. I have 5 lbs left over for food.
OK, I cheated by putting so many things into the utility bag instead of listing them separately. Also, I went over the limit on total number of items. However, I have spent many nights in the the woods of the White Mountains and the Adirondacks with the gear on this list, and I know I can survive for many days with it.
Please note what is missing:
1. Gun. I have never needed one for self defense in the woods, and it is difficult to subsistence hunt while injured. I know I'm an outlier in this sentiment on a website populated by gunowners, and I own a good number myself. I would take one if i were allowed to carry more items, but I would choose the sleeping bag ahead of the gun if it came down to leaving one at home.
2. Fire as a substitute for a sleeping bag. This situation requires a fire for signaling to rescuers after they locate the downed plane courtesy of its ELT beacon. If the ELT was destroyed in the fire, and I am injured, I could not gather enough wood to keep a fire going 24/7 and I will die of hypothermia without the sleeping bag. I have a lot of experience with the process of gathering wood, and it requires tremendous physical stamina, not to mention daylight because you can't see well enough to gather wood after dark. Fires burn an enormous amount of fuel. Every outdoorsman should spend a day gathering wood for a campfire, keep it running for 24 hours in a cold rain, and then make the choice between a sleeping bag and a fire for your primary survival heat source. The sleeping bag wins every time.
In truth, all small planes have ELTs which will activate at impact, and will send out a signal for long enough (before it gets destroyed by fire) for the nearest Russian spy satellite to hear it, identify your location, and then the Russians will notify the US or Canadians of the site. They do this with many plane crashes. Help will arrive within a day or three, and you need to be able to hold out that long but not much longer. I would not get into a small plane if it did not have an ELT. Give me that sleeping bag.