I propose that nations be allowed to Takeover regions that don't count towards the noble/region limit.
These Imperial or Hinterland Regions would eat half the food of normal regions since they are more self reliant. They would also produce half the normal food and gold of normal regions since they keep them. All gold would go directly to the ruler rather than a duke. No region lord can be appointed. Takeovers would go twice as fast since they are less loyal to "their" realm. Less likely to go rogue since they don't pay as many taxes. More likely to switch loyalties to other neighboring realms, especially if next to a Noble-Ruled Duchy Core region.
Exact ratios open to discussion. I used half as a starting point that seemed good.
Basically looking for a way to allow realms to expand their influence beyond current borders but have that influence be very sketchy. When frontiers meet, regions could flip back and forth depending on which nations they have favorable opinions of. And of course having a tendency to prefer joining a more closely controlled Noble-Ruled Duchy Core region next to them.
Nobles could influence future turnover via doing some of the things we currently have that make citizens like nations more or less. Could make for some interesting "non-combat wars for influence" on the edges of larger empires.
