Well, the only way around this is to set up your own USER performances.
Most of the presets use PART 2 as the Bass part. PART 10 is of course for the rhythm. I've also noticed that PART 3 is usually piano.
I always try to make sure that my performances go by a certain paradigm. I keep all of my pianos on PART 3, all of LEADS and FX SOUNDS on PART 1, BRASS on PART16, etc.
This is not the best way, but it lets me know that, if I sell my keyboard and get another one, I can just set the sounds accordingly on the new Keyboard/Module becuase I know where everything is.
The Infamous EPU.