BC, you could do that, but if you want just bass, it will automatically play across the board in full keyboard mode..
Set the split point[I usually set mine at F3 on a 76 key unit] when you would like left hand bass and right hand piano/organ..
The bass patches are considered synth sounds, you will not be able to split , let's say a left hand bass and a right hand scat..
All your set ups are easily saved with a name in a user spot for immediate recal..