IMNTBCHO, if he tells you he can correct that stance, he's a legend in his own mind. And, I'd bet a dollar against a donut hole that the same hoof conformations that are present in front, to some degree, manifest in the contra-lateral hind. And, if you don't address the hind end issues(if any), you're never going to really help the front. At the rising trot, always post the right diagonal. Well, considering you've gotten along OK for the last five years, and based on the written and photographic record you presented, waiting a few more months shouldn't be a problem. What is a problem, at least for me, is that your farrier doesn't seem to have a better grasp of the situation/issue and an appropriate protocol to manage it. Also, IME, the shoulder 'problem' is the result of the hoof problem, not the other way 'round. Part and parcel of the overarching problem. You are fortunate to have a horse with 'high' withers'. They help hold the saddle in place. Out of couriosity, are you stirrup leathers the same length or has one become more stretched than the other? Part and parcel of Hi-Lo Syndrome. No, no and nope.