Best of luck to you @RichG. I did quite a bit of windows admin with IIS back in the day but I couldn't explain to you now how to do it without being on your system.
If you still can't get IIS to play nice, may I suggest giving WAMP a try? It's basically the most popular linux web server: Apache, on windows. It will allow you to stick with windows but also use the suggestions and instructions from the nodebb documentation to get your proxy pass setup correctly. Additionally, configuring wordpress to use Apache instead of IIS is trivial.
If you decide to go this route I can walk you through setting up apache and the vhosts required, just start a chat with me here.