Go to a local welding shop and get a 2" wide end cut from a 12" C-channel, have them bore a hole in the center large enough for a 1/2" lag screw. Hang the stand, place the C-channel over the riser bars so that the flanges of the channel surround the bars, then drive in the lag screw. Enclosing the shaft of the lag screw with a short length of metal tubing or pipe will deter hack saws as long as the tube rotates freely. The stand absolutely will not fall, and since nearly all stand thieves carry bolt cutters it will be there when you return. It goes without saying, but never leave your climbing stick sections on the tree when you leave, it just makes it easier for the thief. BTW, you probably know your thief, I'd hang a trail cam with the flash disabled.