Trail cams are useful after the fact and may be a deterrent if thieves know they're there. I'm presuming the OP wishes to act rather than react. Keep 'em from pilfering wood to begin with.
Any potentially harmful solution to thievery could land one in a heap of legal trouble these days. It's a sad reflection on society but true nonetheless.
Thieves go after low hanging fruit. The harder it is to steal and the higher the likelihood that they'll be caught, the less likely it will be stolen.
My father-in-law sold firewood in the 1930s. Fuel wood was more of a necessity then and like any fuel, was subject to thievery. He'd wrap stacks around top and bottom with a steel cable, draw it tight with a comealong and lock it down. This method wouldn't stop a thief with bolt cutters but few petty wood thieves carry those.
Other proactive methods exist ~ stack wood inside a fenced area, make sure someone is home most of the time. Cars parked out front help, gives the impression that someone is watching. Motion-activated lighting is a good deterrent. A pair of German shepherds inside the fenced area would cause me to think twice.