This is a pretty awesome idea, IMO. I personally wanted to emulate a golf course at one time, for not other reason than I thought it would look cool to take the idea of natural scaping on something man made. Needless to say, as I started planning it out, I realized I am not into golf and it would take a lot to do so. Another idea I had was to make a fish less tank, recreating a favorite/famous skate spot but realized I didn't have the time to make tons of concrete forms.
Sorry, long back story, I just like the idea, even as someone who has never been into fake plants, castles, shipwrecks, etc. Just saying that with a real plan, very cool.
If you are using moss, I would almost consider doing a bare bottom tank so you can maintain the brown sand more easily. With proper trimming, fissidens fontanus could probably look like grass but it is a bit dark. HC may be a better color but would also be much more involved.
Another idea that could be really cool is a shadow box background. You could take an image and have it printed on something transparent, almost like an old school projector slide. Here is one of many examples, search "shadow box aquarium background"
You can back light it with LED strips, I am a huge fan of RGB but you don't really need that, but it could be cool.