I always thought a flat cap of 40 people per area was perfectly reasonable, considering the enemy often has FAR more than 40 people holding a position when you have to attack it, and I've lost outposts with 2+ infantry squads backing up a 40 man garrison, so I'm not sure what we're expected to do against assaults where you get railed by 3 transport helicopters, attack helicopters, armor, jets, etc.

This should either scale with war level or just shouldn't be a thing. Antistasi has always placed a reasonable emphasis on gathering manpower, so why should I not be able to allocate it to defend my holdings better? Some places already take massive battles just to get them in the first place because of how heavy handed the AI response to attacks is.