Shelter, maybe a tube tent they are small and light or a light weight but sturdy tarp or poncho. I suspect your greatest threat will be the weather.

Being warm and dry when it is cold and wet, or shaded from a too hot sun is what will make a difference. It will help with your physical needs and keep your morale up.

I was able to put together and EDC type of kit that you are suggesting, in a Maxpedition Jumbo which can also carry a 32 oz water bottle. I have since moved away from that concept but I revisit it often. How are you planing to carry some of the larger extra items?
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"The reasonable man conforms himself to the world around him. The unreasonable man conforms the world around him to himself. Therefore, all progress is dependent upon the unreasonable man." Unknown