If he's a dressage horse, use it to your advantage. If he does dressage, he knows how to do a shoulder-fore. Learn it. Whenever you sense he's about to be goofy, put him into shoulder-fore. He can still spook, but he can't take off with one leg displaced under his center of gravity. Also, I don't know what type or riding you are doing with him, but this sounds like the type of horse who needs to be ridden on the bit rather than slopping around on a loose rein where he can lose focus and gawk at everything around him. Keep his mind engaged, change your gait, tempo and direction frequently to keep him thinking. I agree with others about the one rein stop. It is fabulous at preventing spook related bolts.
You just have to see your distance...you don't have to like it.