With the addition of improvised rope it would make it feasible to require an improvised sling made from rope, or a pre-made sling to place items on the pack inventory slots. Ideally there would be no separation between a gun slot and a melee weapon slot. This would encourage pack-able/collapsible guns and force players to make difficult decisions as to which weapons to keep in the early game as having an axe and a gun will not be trivial.

This could further be balanced to require a longer animation to move items from the backpack to the hand slot vs sling slot to hand slot. Once implemented, the stamina system will also have a natural balancing effect against excessive gun carrying due to relatively heavy weights.

I realize that this would involve adding an attachment slot to all two-handed items, which is not without its costs in manpower and time. This however, could help alleviate other gameplay issues that have been cropping up since the addition of vehicles and as more mechanics that require empty hand slots are added.