If you are training for SMS, he can't bend his head. He must respect your space, and move away from you when you step toward him. You do not have to beat him to get this, but you will have to enforce it, and make it uncomfortable for him to ignore you. My suggestion: Do warm your horse up, have him trotting off well, backing well, trot a few circles and figure 8s (you will be pretty well warmed up by this time too). Then set him up. A pivot is a FORWARD motion, so pull him slightly forward, don't let him back up, and step turn your attention toward the pivot direction you want, and step toward him. You will be just behind the throatlatch area. Hold your lead in both hands like you usually do, but if your horse doesn't step away from you, drop your near hand, and poke him in the shoulder with your thumbnail. Let him take only one step at first, the best would be if he crosses over first, but my horse rarely does that either. At first, be happy with one step in proper form, without moving his hind end. After doing this well several times, or several days, ask for the second stop, always insisting on proper form. If he moves his hind end, or steps back, move him forward and try again. If he is so "stubborn", perhaps you might want to hold the business end of your spur in your hand, but again, don't whip or jab at him, just press, make him uncomfortable enough that he steps away. Just because "they" beat the crap out of the horse, doesn't make it right. SMS is supposed to be fluid and with hidden cues, how can you get that response with big, beating movements?
40+ years owning, showing and loving horses....including teaching