This may sound kind of stupid but what do you think of having a group of smaller /sub companions, that woudn't be used in battle and general adventuring, but yet woudn't be complitly pointless .Something similar to Suikoden ,
Assuming you get a stronghold, you could recruit a bunch of characters, a shopkeeper , a blacksmith, a cook, and so one every one would have some function that would add to stronghold, and maybe even make so that you could take one on normal adventuring and get some uttilty abilite ( either by puting such non-battle in one companion slot, or making something similar to what they did in Might and magic 7 were there was one slot for just such character.) for example, you can only make use crafting near special place , but with blacksmith you can do it anywhere, and so on.