@Seamus: Excellent news! Well done on finding your way through all of this. Now you have a way through I am sure it will get easier. :-) Look forward to seeing the updated answer with this new learning
@ukBaz: I wish I were as confident that things get easier as you :) While I'm happy to get this working, the lack of any apparent coherence is not attractive IMO.
@ukBaz: I have a proposition for you: I have earned some "credit" for the question, but I am not keen on preparing a proper answer for this. AFAIC, you deserve much of the credit for beating the path through this thicket. Honestly, I never would have made it without your suggestions. I'd propose that you prepare a proper answer, which will be the "accepted" answer. It's a pittance, but "reputation" are the only wages here on SE :)
My "answer" is actually a "blog", and I plan to publish it on my GitHub site. That allows me to make revisions to it as things change & hopefully keep a current procedure, while maintaining older versions/branches as historical reference - or for those that are running "behind" the current release.
@Seamus: The most valuable thing for me will be to have a reference for how to do this. So your blog sounds like the most rewarding thing for me. I am not overly worried about a few extra reputation points, especially when you have done all the leg work. It has been a fun collaboration. I don't think either of us could have got this result on our own :-)
@Seamus: I understand about the time needed to put an answer together on such a big topic. I don't have a RPi right now available to put a Lite image on. It would be cutting and pasting bits from our discussion and the answer you have so far. Not ideal. I'll see if I can get a couple of hours over the weekend. If I can do something reasonable in that time then I'll post it. Otherwise, I don't see me getting the time in the foreseeable future. :-(
@ukBaz: OK, but I won't let you get away with that excuse for long when the image-utils (or from here if you don't git) script is available :) It's just too quick & easy to make an image :)