Obligatory first post, long time forum lurker, hundred of hours played etc.
I feel like the current backpack and item system could be vastly improved with some modifications. The new backpack model, as others have said, has made me wish for various backpack models to equip. Similar to other clothing slots, you could find better backpacks and make your own out of hide. The items would have durability and could be damaged by blizzards, struggles and time. Imagine the desperate scramble, after a bear mauls you and rips your backpack open, spilling your items on the floor. You have seconds to choose which items to grab and take whilst running away from the bear.
Obviously, this would make carrying all of your items in your backpack more risky. This could be offset by pockets on clothes, giving the jackets and pants various carry volumes and allowing you to keep some items close to you. For example, you are tired and need to climb that last rope, you drop your backpack, going up the rope with only your clothes, matches and bandage in your pocket and a revolver on a holster.
This could also be relevant to draw time on weapons. You cant quickly whip out your revolver or flare to deal with a wolf if it's in your backpack. Its a safer bet to carry your rifle in bear territory than have it holstered on your back in case you need it in an instant, etc.
To deal with locational storage, it may make sense to give items volume as well as weight. Lets face it, your rifle doesn't actually go in your backpack and you don't really want to walk around with 10 cans of peaches in your backpack. Unfortunately adding volume in addition to weight would require every item to be rebalanced and would be a huge test load for hinterland. (A good example of this system in action is NeoScavenger or even the Resident Evil series).
I feel that splitting up your item storage would allow for greater roleplay and more considered choices before heading out into the world, keep what is key close to your body. The downside would be item/inventory management would not be as streamlined and simple, however in real life you keep your phone in your pocket rather then in a backpack so it should feel intuitive.
I feel I saw a similar topic to this months ago but let me know how you feel!