Note that there are two versions of this map, "guided training" and "freeform training". In free-form there are more items at the start.
The most consistent way I have found for this map is to use Terry Norfolk (Man in white suit) to attend a meeting with Kalvin Ritter (Target) as its an easy Silent Assasin.
Easiest way to get his disguise is to use the coins on the box in front of you at the start, lure Norfolk over to your start point and knock him out. There are no enforcers or real limitations for Norfolk, so just walk aboard, talk to Ritter and then go to his office and kill him however you please.
Exiting the mission will pop the achievement. Quickest exit from the office kill is the helipad above.