So obviously balancing is an issue right now, what are some ways to improve and balance the items more effectively without it being pointless?

Stopping boxception is one way, however for now ill leave it as is because why not.

For the backpack im thinking of only allowing it in the outerclothes slot (diving suit & armour slot) and removing the ability to hold it in any hotbar slot, this would add a huge balance in that you couldnt take them outside the sub along with your diving suit unless you held it in your hands.
The same could be applied for the Duffel Bag, but with only hand slots instead of the outerclothes slot, but that slightly nulls the whole point of having it.