another thought i had was being able to trade administration like you have an outpost that has a small region and a large region could you trade the extra administration to another region ?
The goal of Administration is to make managing large settlements difficult. Being able to import it would cheapen that, I think. Once you have bronze it isn't difficult to fully upgrade a town center, which results in a lot of excess administration for a small settlement.
You can keep growing settlements by externalizing some resource production and shipping it in. When religion is introduced you'll be able to increase administration for a cost, and a trade-off of other bonuses.
I too was having an issue along these lines, I had started out on an Island and had advanced all the way to full bronze everything, when I suddenly realized I had run out of administration. Without administration to build I then was confined to my lonely fate of eventually starving to death because lack of food, and lack of ways to make food or new space.
This got me thinking, the fact that every city is doomed to slowly starve to death due to lack of administration is a weak point in the game, cities should be allowed to prosper until a raid or enough unrest that will engulf the city into turmoil in due time. However as I was reading the discussions here and there, looking to see if someone else was voicing the same difficulty as me. I found this comment, and I understand that having a source of income or a way to continue to upgrade an administrative building would negate your idea for the cities of "Quality over Quantity". So that did away with my idea of suggesting a "Library" building that slowly gave administration to the city. Thinking along your lines of quality over quantity I decided upon suggesting a alternative to just giving the player more administration until they just reach the boarders of their region.
My alternative is that you change the food stat in a city (which is currently a almost static resource, I think it should be more like grapes or tin or one of those kinds of resources that have a indicator to show if the resource is decreasing or increasing) if food is based like that, I would suggest that food be a tradeable resource. Doing this will allow for the player to import food into a city that has reached it's peak administration capabilities, saving the city, from starvation, not unrest perhaps. This I believe would follow your vision "Quality over Quantity", in my playthroughs I found that I typically settled where I could find the most resources to help my colony expand to it's fullest potential. This tactic though somewhat historical, makes it that the large open grasslands and forests remain unpopulated and unused, I believe that by allowing food to be exported and imported, places like the fertile plains or the densely wooded areas would become useful, like a grasslands colony to export food to a forest colony that cant make enough food alone, then that forest colony can export its resources to places like the grassland colony to create more stuff to feed more people etc... thus creating a full circle of supply and resupply for your game.
I believe that it is in your hands to make the best choices for your game and I cant wait till the next update. I hope that the ideas I tossed around will give you even more tools to shape this game into what best suites for vision.