Why don't you use an mp3 player in the background? www.vuplayer.com is a light and good one that I use for several versions for years now.
This way you can listen to whatever music you want without it stopping unless you choose so.
__________________
That's it, keep dancing on the minefield!
Wav files are larger (and better quality) than MP3. But I think you can only go up to about 4MB in a single file.
If you want to use the battlesounds for music, you may be better off sticking with mp3. Besides, you would have to edit the .ini file if you wanted SPMBT to play MP3 game sounds but wav music.
I assumed the battlesounds play one after another, and reset when you restart, but not certain.