Max I could imagine would be some HoI3 analogue, where division could be only token thing and most equipment, personel etc granted by 3-4 brigades attached, Similarly ships, but how to make AI using it properly is a bottleneck.
Shipbuilding is much more in my concern, there should be independent mechanic outside of regular IC, i.e. using port levels as equivalent of IC only for building ships, kudos for someone who program it into work