Kudos on you Sarge. For most of us there is no magic to learning a difficult tune. You work your way through it and modify as you go along. Playing it over and over again will finally kick in the "muscle memory". After that, a person can kick it around and see what falls out.
Many an old song has become a hit because somebody dug it out and kicked it around some and modified it a little.
I have yet to try this particular tune but look forward to trying it out.
Keith, I just now got to listen to your video. I think you are progressing nicely. You made a good choice using a tremolo on this song. I like sound of your baritone uke. How are you feeling about the progress you have made?