Hello,
Please give us the ability to set custom boundaries and assign certain stations to the limits of said boundaries. Pretty much let us mark our own districts for our stations to receive calls in.
This would be good for keeping your units in the intended area so they don't end up on the other side of the state. You could even make it to where a confirmation message displays when you attempt to move units outside of their designated districts. These said districts could be marked off by setting markers (much like the POI markers) around the desired area and when submitted the area within the markers is a new district. Only stations assigned to a specific district will be able to receive and respond to calls in that district only (unless you confirm to respond M/A where it asks you if you want to move units out of the district.)
I hope this makes sense; I feel like I repeated myself but I hope you get the general idea of what I was trying to get across. Thanks for your time!