How about a fake camera with a timed detonator that gets activated when the camera is grabbed, by the yank on the strap? Maybe filled with a little willie-pete?
That might work! A lot of crime prevention comes from situational awareness. I've played tourist in other cities, and when people started looking dicey I hid my camera, and or hightailed it out of there. Doesn't matter where you go, Seattle, San Diego, New York, Philly - be aware of those around you.
One time me and a co-worker were walking not far from where this cameraman got robbed, and we saw a man counting his paper money out of his wallet while leaning against a building. Just as I was about to comment to my co-worker about what an idiot the man was, some guy ran up from behind us and grabbed the wad of paper money from the guy's hand, leaving him in shock. The thief was gone in five seconds around the corner. Be aware of your surroundings, and better yet be smarter than that victim.