I agree with the whole stick and bag thing, but have you ever rubbed a plastic bag all over him? I also agree with the whole taking off the jacket like an idiot thing as well, you never know..... Have you tried to put a tarp on him and have him walk (did this with an Arab mare, she even stood tied and let me drape it over her, after a few lessons of course). Have you also have him walk over the tarp (again did this with an Arab mare, first she thought it was going to eat her, than she realized it wasn't). Have you attached something to his halter to get him used to something flapping in his face? Drop a cloth on his head (again did this with a Arab, and tolerated it). Getting him used to as many sights and sounds as possibly is probably the best thing you can do. Because than he knows that those sounds won't eat him or cause him harm. If you would like to know more natural horsemanship, just PM me, and I'll try and be more of help. Just trying to keep this short and sweet.
Note: Trust is a huge issue. The Arab mare that I did half the stuff with, if I didn't have her respect and trust, she could have exploded at anytime, and hurt herself or myself, but because she trusted she tolerated everything I did with her, with a smile on her face despite the fact she was probably going, "I'm not gonna like this. But I know you're not gonna hurt me." Another big thing is treats, they are your friend, but only when timed with the response you want. With her, even if it was a second of relaxation, she go a verbal praise, the 'spooky' object taken away and a food reward. This taught her that relaxation is a good thing, even in the face of something spooky. This also works undersaddle, if you have his trust, and he sees you as a leader, he won't react as much. Trust me, when you have their trust, you can do just about anything.
Abuse is never the answer.
Think before you act.
Never act out in anger.