I don't have a great answer for you cuz i just don't know if cotton would work. I think it might if you can hold if in place and you don't pack it in too tight.Trial and error I guess. The problem I can imagine would be if the cotton moved around and got under your toes. Why don't you try it on a practice steep downhill slope. My thought is that if your foot is not slipping why would it matter if the shoe is too long.If the boot fits in the arch,instep and heel OK then lace up tight and go out and try some downhill area. How about calling an Adventure 16 boot specialist and ask them?Good luck.
