I have found that the easiest way to crupper train the difficult horse, is to put a training surcingle on them, and connect it to the surcingle. I have done this and let them wear in the stall while they were eating a meal. They can't really do much in a 12 x 12 box stall in the way of hurting themselves, and you can have the chicken way out and not have to ride them while they learn. :)) Once they get used to that, lunge them with it. They should be ready to hit the trail after only a few times.