With more enterable buildings coming in a future iteration, it would be cool to have lockable doors or storage cabinets. Whether the keys would be universal or specific to certain locks is up for debate, but it could a preferable (or more risky) alternative to tents. Obviously they would need to be very rare to prevent stockpiling (perhaps being lootable from certain zeds) and would be part of the players inventory and, therefore, at risk of theft.