Perhaps too late now, but there are a couple of tweaks I'd like to see to make it simpler to mix and match party composition.
1) While in camp, allow free management of inventories and levelling for all companions in camp.
2) When you're exiting camp, present a dialog to easily let you pick companions (a la Mass Effect or Dragon Age). This can have your most recent team preselected so it doesn't slow things down.
In my opinion this would encourage players to think about the challenges ahead and select the most appropriate team, and not just stick to the same three companions because changing them is such a chore.
Prof. Dr. Dr. Mad S. Tist 