A while ago someone posted satchel bags as an idea forum after I suggested it in the discord, I just wanted to add a couple of things so here is my edited suggestion.
Simple, a satchel bag (like a purse or book bag) that goes onto either of your hips, (not the hip slots) or back, and has 2x2 storage capacity. The satchel bag must be held with 2 hands to take it off (mainly for climbers so you don’t accidentally take it off) and a flap is covering the storage zone so you don’t accidentally pull out your items, this can be lifted with one handto access storage with the other hand, or can be left open to grab a two handed item out. This bag will be mostly for climbers and adventurers who still want to have storage, but want to be faster and lighter.
A lot of people have been saying that there’s nothing to keep people from wearing a backpack, and or multiple of these, allowing for an immense amount of storage, and I agree, I think a satchel bag should only be able to be worn when the user is not wearing a backpack, and only one satchel can be worn at a time, leaving you with your four tool belt slots, and four slots in your satchel bag. Perfect balance of little weight, and amount of storage.