I'm nowhere near as far as others, only a little ways past the Stag Lord, but I made 3 specifically ranged characters so that even if I'm not actively casting spells, everyone is contributing.
My main is a 2h fighter, and also the tankiest, which isn't really saying a lot probably. Then I've got a druid and a rogue for my melee, along with the druid pet and a ranger pet. The pets help a lot since I'm not the sturdiest up front. I'd be a lot better off if the rogue were able to rape faces more with Finesse Training, but since it's bugged that hurts a little
For the back row, I've got the ranger of course, an Eldritch Archer Magus for the arcane casting duty (I love this class honestly, using a bow to deliver spells is awesome), and then my cleric that I started out as a Divine Huntsman Paladin for 2 levels, so he's got all the bow proficiencies and the paladin resists. I slacked pretty hard for healing at the beginning, with only a couple CLW and LoHs, but after level 5 or so that sort of went away.
Does level of the other companions matter at all for their ability to handle the kingdom stuff? It doesn't seem to, but that's potentially something that could hamper you. And I was going to say those tasks where you are forced to bring one along, but then I realized you have 2 free slots and don't need to drop anyone.