Good looking Mule saddlesore.
FWIW, I had a friend once that had the same problems on trails with cyclists spooking his horse.
He rigged up a trike (full size bicycle with three wheels and a basket on it) with a set of poles like you would pull a cart/buggy with attached to the handle bars.
Then he would lead the horse around with it until it got used to it.
Then he rigged it up to pull the horse behind him and would ride in front around his arena and on long straight aways.
He had to play with the pole/rigging set up a little to get it right and moved slow.
Good Luck,
Ted
PS = Forgot to mention that once his horse was a little used to it, he used to leave it hooked up in the arena and let it pull it around by itself while he sat over in the shade and had a cold one...............
