Note: when I was initially testing this, enemies would only aggro based on line of sight. The fact that they aggro to gunshots makes the beginning significantly more difficult, but still just barely possible.
Not sure if it was intentional, but at the start of the level, if you go left or right, you can walk up to the guy holding a shotgun or the guy holding the ak right next to him, and take it before anyone even shoots. Grabbing the ak at the start of the level made it pretty simple to complete. Regardless, it was pretty good.