Could always hook them to a live power supply (if they are metallic and not CF) overnight......you could have a thief christmas tree
Had a bike stolen right outside the front entrance of a tescos express a couple months ago........then a month later, I had the new bike locked up with two locks, so the kids who were hanging about outside didnt have time to steal it, they just slashed the tyres instead......no fear of the camera directly outside.....or the dozens of people that mill around this area going from shop to shop etc.....astonishing.
I still remember when the first one was stolen, just as I was leaving the shop, this woman said to me 'I think that man out there is stealing your bike'.....a good 8 people just stood and watched him do it, clearly knowing what he was doing and didnt even think of shouting out anything to put him off. Common sense would dictate that in that kind of environment he is going to run, not try it on with you. Different if it had been a lonely alley..
One thing I like about being 6ft and very large, whenever I see someone about to do something like that, I've no problems disturbing them....so far none have ever confronted me, just fled......although I do wear a long mac done up, so perhaps they think im old bill..lol