You can still do it. It doesn't have to be in the city. My idea:
You and your spotter are sent to a location to plot enemy patrols. Another sniper group, watching the enemy base, report in and say an enemy sniper team is headed in your direction. He sets up position north of you, and a friendly patrol reports they are pinned down by an enemy sniper. You must take them out, but the shots signal east and west alike. You must support the men then, so its not just a counter-sniper role.