I think I should tell you the trick a guy used on Keno. I wouldn’t do it, because I don’t want to ride horses like that anymore, but in the end I had Keno over everything except for trying to turn, close his eyes, and dead run into objects.
The guy I gave him to is super handy, and he also had the same problem. He couldn’t get along with him at all, and said he was suicidal. Lol. He would be good, and then do the exact same thing, but he was brave enough to take him to work on flat country.
He hated him though, but an old hired man decided to ride him. He didn’t care, the guy is not exceptionally talented on horses, but what do you have to lose with Keno? He does however have some old tricks. We don’t tend towards tricks. If you can’t get by him honestly, why do it? Yet, I see the value in what he did with Keno. The horse is used for everything by this guy and his little grandson, and he’s fairly dependable to be honest.
What he did was take a rope, tied to the center ring of the cinch (that ring for clipping your breastcollar or a tie down), through both rings of the snaffle, and back to the cinch. Then he just rides him. The horse is stuck giving to that pressure all day, and obviously unable to push his way out of it. He is thereby unable to get his head up or to the side enough to really run away.
Now, I’m not recommending doing it, but it is a thought you might have in your head. If you did do it, I’m sure you know as well as I do not to get straight on him, because he could panic at the pressure, until he understood it. It’s the only trick I’ve seen that does make sense to keep a horse from the ability to really run away (a horse who can be light, like you described if I’m picturing it right).
I don’t think I’d ever do it myself, because I won’t put myself through a horse who needs such a thing anyways, but it is a thought and something I wouldn’t have ever thought about prior to seeing it used.