It's nice of you to make the effort to help people with this GR, and although I don't actually use that method, since you asked for feedback on it, I thought I would chime in. I think it's a great little tutorial and probably will be a big help to many.
On the subject of other methods, I'm fortunate enough to be one of those people who is good at drawing and painting, and so I have a good head for spacial perception and perspective, this means I can usually determine the AOB purely by eye and usually get it pretty close. My method is not much use to people who can't draw to save their lives I know, but there you go, it's the way I do it.
Nice to see another pilot on these forums too by the way, but unlike yourself flying is purely recreational for me rather than work.
Chock