Zip, I am curious to know if you are trying to do all this training without a knowledgeable person as your guide and mentor? It's really hard to do this kind of thing, and the other things that you need to do to train a horse, all by yourself, without guidance. We have to learn from somewhere, and thought a video is nice, a real human teacher cannot be beat.
If Tonto is a dominant horse, then doing "join up" with him incorrectly will not change his attitude toward you. It is his mind that you are trying to change and maybe doing join up well might help, but you have to have a total change there, not just for the 20 minutes or so that join up might take. So, you can do join up, but if in all other respects, nothing in the way you deal with your horse changes, then it's unlikely that just doing join up will create a huge change in your horse. He will probably still continue to be a dominant animal.
I don't mean to sound discouraging, I just don't want you to think that it's some sort of "magic".