Start with it on. Do your run. Turn it off.
While it's on, they may not notice it's a projection. (consider percept 3 Int 3 -2 for distracted, other situational modifiers may also apply.) Even if they do, it doesn't say they get a good look at what's inside the projection, just that they know it's projection.
So everybody wears their halloween costume for the job and at the flick of a mental switch they're out of costume and look like someone else -- who is obviously NOT wearing holoware.