Can we build remot station or guard post thaht will be abel to harvest resorces from a distant tile, or i must to build another pionier and go build a city ?
There are many knowon gold, salt or whatever mines and goodie spots harvested by a distant city using only a guard post there and sending some metrials to city 
Solution: Guard post over resorces with some guard unit, who controls it after build, get the stuff. If in oposit region, half of stuff gos in But border starts to shift slowly. To encourage players to take it back.
What are your ideas ?