One more follow up from me. OK I realize now that I don't have to do that big elaborate setup with the cue against my chest. The important thing is just getting my chin really close to my left shoulder (even slightly over the top of my shoulder). This naturally pulls my other elbow behind my head.
I think the OP who had a lot of trouble turning his head that far - one possible explanation, is that if you have rounded shoulders, and you try to turn your head far to the left then your chin might actually start pushing against the side of your shoulder which will make it seem like you can't turn anymore. The solution is you need to go up and over and down with your head to clear the side of the shoulder. Seems obvious in retrospect.