So I had a thought.
Instead of assigning a bed to a particular character, why not assign doors to particular characters.
It would work like this, I build a shop for the blacksmith. The blacksmiths shop has two rooms, the front area allows everyone to enter and exit because the door is left unlocked. But I could give the key for the back bedroom to the blacksmith. That way only he can get into the back room.
If I want multiple characters to be allowed through a door I would hand out multiple “keys” to the door. It seems more “real” if you made the game work this way.
I did a gameplay video demonstrate how this would work.
Also Im getting a lot of people saying that this is more work. Its not. Currently you have to click on one person and then assign them a bed. That would count as one action. It would take the exact same number of actions to assign a bed as it would to assign a door.