Found this a real challenge with an entertaining finish, when the penny finally dropped. Thanks Elgin.
It's certainly a nice construction, and an impressive set of clues given the constraints, but I'm perhaps not quite as enamoured with it as other posters here. If anyone is stuck at the end, I found it slightly underwhelming than what the descriptions here had led me to expect! You have most likely done exactly what you were supposed to, but have got it slightly wrong, thanks to an elegantly prepared false path...
I never really made my peace with a couple of clues - 12a, 31a, 42a, 38d - and wasn't a huge fan of the multiple (non- thematic) names. Any how, that's small fry, thanks and congratulations to Elgin.