I don’t totally understand why you are doing all this. It is your choise to put container in the path that will be wordwide visible if you do a small mistake, but that is your choise. But everything else… why?
To have a reverse proxy front of Discourse is really trivial and otherwise your setup would be a standard install without all that hazzle. Sure, if you want to play and that is your hobby, but quite soon someone will pop-up and say you can get support only for standard install and the biggest issue is anyone actually doesn’t know what you have done. Or why.