Random battle theme

I just had a random thought, but am unsure how possible it is:  having an overworld battle theme based on the battle background (eg, deserts, grasslands, and forests play an overworld theme), and have the rest of the backgrounds play the default theme.

Yes it is possible, it's not a much elaborated ASM hack. If it's the battle theme, you check the battle background ID ($11E2) and make as much CMPs as you want to check battle backgrounds and load the good song.

Would it be asking too much if someone did a patch for a different music track to play on overworld backgrounds only? If the patch was an asm that pointed toward a free block of space that I can define, then I am confident I can import the music myself at that space (although I am a noob coder and will learn as I go)