I cringe every time I see the video of Always Dreaming lunging about on the track, sometimes way overflexed with nose on chest - probably an old video, hopefully he's going better now, but I have to wonder if anybody from that barn thought to try the chambon first. It's all elastic, adjustable, runs from the poll, through the bit rings and to the girth - so out of the rider's hands.
Go slow and set it loosely to make sure it doesn't freak the horse out, first just walk around the barn, then take some time jogging before going on to gallop. In our experience, most horses find it a calming influence and those we've tried it on showed immediate improvement, eventually to the point of not needing it at all in a fairly short time. The chambon is so rare on the American racetrack that we kind of hide ours as a "secret weapon".
https://www.pinterest.com/pin/378795018647867045/ - here's Always Dreaming overflexed in draw reins