I think Mass Effect and Dragon Age as series handled the problem of what companions do when you aren't with them. They occupy their own place in the hub and do what they need to or like to do.
The entire Mass Effect series companions serve a role in your crew:
In ME Tali is presiding over the engine of the ship.
In ME2 Garrus is always calibrating weapons.
In ME3 Liara is
||operating the shadow broker network.||
In DA:O they sit around camp but are relaxing, like Oghren drinks.
In DA2 they actually occupy their homes, like Anders is running a clinic.
In DA:I they all occupy parts of Skyhold and act as your inner circle, like Iron Bull rests in the bar and commands his mercenaries.
Bioware figured out in those games to give companions more natural activities, and they do range from contributing to the group to sitting around and relaxing. So I feel if Larian wanted they could give each companion a camp role or something to do, even if that something is staving their own boredom.
