While Raccoon28200 is not wrong in that this Trophy isn’t hard, that’s not really a guide to quick completion, in my opinion.
For me, the area just north of the central big church/plaza of New Orleans around the gazebo is full of opportunities. While “ledge-like” overhanging branches and wires between buildings certainly apply, so too do the T-shaped light fixtures... and this area has all three in good supply.
There are plenty of guards standing around and even some on patrol around the church. Hang one guard before he completely notices you (full yellow triangle) to get the ball rolling. Once you have that, take them north to the wire between the buildings. The guards won’t climb up after you to the roofs, so up you go.
Once there, go to the wire between the two buildings and whip downward even while being shot at. They won’t get out of the way of the whip when you flick it down at them, so grab a guard and hang him. From there, just proceed to keep guards active and go for ten (or however many you have left), climbing, on wire, whip to hang, repeat!