I occasionally live that backpack life, and this accessory organizer medium by Cocoon is my new friend. 

It’s simply a hard rectangle of criss-crossed elasticized bands that you can fasten a bunch of stuff to for clutter-free carrying. 

This one has a zipper pocket on the back, and slides easily in and out of any pack.

Popdiatry occasionally writes about non-shoe accessories in this section called “Off The Path”.