So we started gathering packs to take to our makeshift base after persistence was fixed Wednesday. Got up to the air fields and started picking up packs to lug back as replacements and inventory holders. Started stacking DIFFERENT colored backpacks inside each other and noticed they were not taking up the entire pack they were placed in. If you take a green backpack (Taloon OR Mountain) and place a different colored one inside of it then you will still have 2 rows of storage at the bottom of the first pack. This only works by alternating different colored backpacks, but you can make infinite stacks from what I've seen so far.