Thanks, this is pretty much how I have been doing it.
Do you know if eliminating bass or drums by simply pulling down the volume to 0 on TTS-1 is still using resources as if it were up?
If so how would you fix that? I assume erasing all of one or the other midi data in the PRV would be tedious.

Yes...you are still using system resources...you can freeze the track you want to and that will free up your resources.