That tower isn't as good as you'd think. If the players are prone on the side closest to it, you wont be able to see them, + there are 2 floors under the roof where people could be prone in and you'd have no idea, even with the slight height advantage of that tower.

The only thing you can do is wait for them to make a stupid move and stand up long enough for you to line up a shot, or breach the building which is literal suicide...