If you have any reiners or working cow people in the area, find out who they get to break colts for them. Then hire that guy to get the horse out. They'll be better able to sit whatever your horse throws at them and can probably get them over that issue.

Unfortunately you will then have to be able to be consistent enough to keep up with that training, and that's not something every rider can do. Yes, I realize you've said you've gotten lessons for a long time and that you yourself give lessons, but I'm sorry, any schmuck could hang out a shingle. Hell, I could hang one out, and I really am not a good enough trainer to be telling people what to do, and I've been doing this for a long time, and have ridden a variety of horses of a variety of breeds at a variety of training levels. I've shown up to a national level and screwed around camping outside. I still wouldn't call myself a trainer.

If you can't find a good colt breaker, if you can at least find a good sized steady-eddy horse that is big enough to get your horse stopped if you can dally up if your horse tries to go somewhere, pony your horse out in the areas where he's having trouble and give him the opportunity to make the right decision and be a good boy. Work up from there.