OK! idea for a lore thing involving the game
the experiment can carry items on their back because of back spines, they can get the item jammed onto it like hooks, making to stay attached via that.
would explain how the bags and all that stay on, could even add it as a limb health bit, connected to the spine , it takes damage when landing on the section, making it unusable when the skin / muscle health is too low due to the area being compromised.. maybe