Not sure if this is obvious, but I'm looking for very simple way to change the default explore music for a separate worldspace, say TR Hammerfell or Morrowind without having all public music also being explore tracks?

For instance, I have a Hammerfell folder for tracks I selected for Hammerfell. How could I simply use this explore folder versus the default when in the separate worldspace?

I've tried both Enhanced Music Control and Better Music System and both seem to not hit my issue on the spot.

For those who are a little more code savy, would anyone know how to create a separate explore folder for separate worldspaces?

You need both mods you have listed: EMC and BMS, but you need to create a mod (requiring BMS) to add the worldspaces you want to BMS. You can use the Shivering isle and Elsweyr ones as examples (they are both included with BMS)