I.m sure it can be done. Maybe a reskin of the Deputy with the traffic vest on. (I heard that reskining personal is a pain) A Sargent? You could make a copy of the Deputy and have him spawn in at the beginning of the game. Just edit the commands of this guy to equip/shoot/etc. Atleast that is what I would try.
I am not sure of this but you will most likely need to divide the bay into 2 separate Virtual Objects(Name them accordingly) then edit LABattalionChief, LAFireStation, and LAFireStationStart scripts.