I echo Allen's recommendation for a focusable Maglite. BTW, cops only get those big 8-D cell models so they can temporarily blind suspects while resting the back end on their shoulders like they see TV cops do. (Sorry, I was a firefighter and we live to poke fun at cops.)
I don't see why a fog machine would not work. I would have everything all set up and ready to expose, start the fog machine, then have my hand on the cable release and fire as soon as the fog seemed right. It might take some trial and error, but what the heck?