The more you can work with your horse as far as desensitizing the better, IMHO.
Tarps, bags, a cow bell, milk jug with rocks in it, kid on a bicycle, walking over poles, follow an open umbrella, drag a board...whatever. He needs to know he won't be hurt and will learn to trust you. I had a mare terrified of the clippers. We got out into the open and I held them out and had her follow. We'd stop, I'd let her look at them, soon I was able to rub her neck and in a few minutes she was standing while I trimmed her bridle path. Desensitizing. No more drama or trauma.
If you ever find yourself in a fair fight, it's because your tactics suck. ~ Marine 1SGT J. Reifinger