Silk Cloths x4/8 or more and maybe Leather and/or Linnen Cloth
One could make a Bigger Backpack, or somehow upgrade the normal backpack, adding 8 more inventory slots.
It would allow a player to carry enough items for a long journey travel, for exploring caves, foraging, exploring the world and mapping the new world (since it would allow more ink, food, maps) without having to go back home every 10 minutes.
It would take a long time and effort to make.
It would reward players a higher degree of freedom, something ONLY achieved after a long term investment.
It would be another item to strive for and to trade with.
It would streamline the gameplay, making the inventory constraints less of a chore. Something players would look forward in the long term.
It fits well it the world, its a coerent idea, it mixes well with the general idea of the "Rangers" set, or it would incentivate a more dinamic and nomad experience.
It could look very cool too, a badass good looking backpack covering someones back, ready for some travelling, exploration, settling.
This idea is so good, how come it wasnt implemented yet?
It would be very easy to implement, we already have the standard backpack model, just change the inventory space, the materials required, and add a bigger/different image for it while equipped and a new icon, wouldnt take more than a few minutes.
edit.
I was searching for some backpacks inspiration on the internet and found some valuable information:
"When you travel, your backpack will become your home from which you live. It will either make your trip easier and pleasant or it will be a cause of frustration and pain, or both. Choose your backpack after thorough research and many, many different fittings. It is definitely worth the effort. Your backpack should be light, durable and comfortable. Your backpack is definitely one item that you do not want to try and save money on in exchange for poorer quality. You will be dependent on your pack, and any problems with it — and there will be more if you buy a low-quality pack — will directly impact your traveling experience. Spend good money on a good pack and feel confident that it will perform for you when you most need it to."

I kept my research for backpacks and I found some cools "handmade backpacks", or some "giant packs" those that use steel as waist buckle, and leather as shoulder straps, while the material used is nylon, ok, we dont have nylon... but thats where we jump the shark and do it with our infinity high quality silk cloth, its so high quality its just like nylon...
Some interesting new look into a Rangers/Travellers Cap with Backpack...

Handmade Hemp Backpack (notice the buttons made of wood)


Another design, size and material, this time handmade Goat Leather (found this one on ebay)



