small pack (open as a container) give 3 extra slots maybe 10 leather working to make few sinews and hides
medium pack - 6 slots maybe 20 leather work large hides and sinews
a large pack - 12 slots and maybe 35-45 leather work
a heavy pack with 17 slots and of course make it require higher leather skill, and require iron or steel for buckles

posted on someones elses post about inventory stack size, but i feel this would be a much better option