I've confirmed that the reason he's always been so difficult is because he has tummy issues. I suspected it, but after seeing a small but noticeable difference in his behavior after giving him Smart Digest Ultra before I work with him, I tried adding a couple of other supplements. The best combination seems to be the Smart Digest Ultra and Aloe Vera pellets (also from Smartpak). So far, the two times I added aloe vera, he turned into mister mellow, as a horse of his type should be.
And after he put his tongue over the bit when we were sorting cattle early in June, I tried a couple of different bits. The advice I found online was to allow room for the horse's tongue. The bit I was using (which he put his tongue over) allowed that, so that didn't seem right, especially when I put a curb in his mouth with a roller, which doesn't allow any room for the tongue, and that quieted his mouth. So, with my instructor's advice, I tried a double bridle. He didn't like that, but he did go nicely with the bradoon of that combination. Today, I put just the bradoon on his regular bridle headstall. He was fantastic! The bradoon is a loose ring, narrower snaffle than my other snaffle mouthpieces, and it's a special alloy and straight, not curved for tongue room. He was much quieter with his mouth than I've ever experienced (except in the sweet iron curb with the roller, which quieted his mouth a lot also). I think that, in Buddy's case, He needs the bit to be as flat and still as possible, and the special metals of each of the bits that quieted his mouth probably played a part also.
I'll stick to the bradoon for this summer, along with the two supplements before we ride, and see if I finally found what works to turn him into the trailriding horse I've been trying to train him to be for nearly five years, and turn him into a true cowhorse, complemented by our dressage training, which we will continue. My only worry is that if he gets excited, the bradoon won't be strong enough to stop him. We'll see.
I also started taking out the fly sheet I bought last year but never used. I decided to put it to use this year. I can't leave it on him when I'm not there because of the danger that he could get tangled and get hurt (not to mention the trashing of the sheet and my money down the drain), but I can let him wear it and have some relief from the flies by taking it with me when I go to catch him in the pasture and let him wear it on the walk to the barn or, like today, after we ride and I let him graze a while just to spend more time with him. It's a closed front sheet, so I have to put it on over his head, but he's so smart, he loves having it on after just the first time, which wasn't bad either. He already knows it means relief! Buddy is super smart though. I wonder how long until he's sticking his head through the neck opening on his own when I hold it up ;)
Later this month, he'll finally get his annual dental work done. That was postponed due to coronavirus.