I use lock boxes and 4" screw bolts to drill the box to a tree ... even that is not fool proof, I had two stolen by some kids last year. Not sure how they got them off but it took some work I know that. These were on public land but I had not seen another human in there in the 25+ years I had been going in there except 4 young wheelie bow hunters on opening day of elk season this past year. I reamed their low life asses good but they still couldn't find the courage to confess. It was a sad day, I had shot my first elk in that spot back in the 80's and had gotten thousands of great trail cam pics in there, I will not be hanging a camera in there again.
I have a hunting buddy that puts all his cameras up about ten feet on a tree you need a ladder or steps, and he conceals them pretty well but does not lock them. He lost a few at ground level and this has worked for him.