Mark, I do quite a bit of LH bass live band playing. TBH, I rarely ever set up the bass part so it sustains... or at the very least, I set it up so a DIFFERENT pedal does Bass/LWR sustain from the main one.

Thing is, when playing piano, you use sustain a LOT, but a bass player simply doesn't overlap notes like that (generally, one note stops as the next plays) and you can muddy up the bassline quite a bit allowing it to ring on.

I'm glad you found out how to do it, but on the whole, I'd stay away from using it much except for unusual circumstances (the LH needs to play something in the RH area while the bass note drones, stuff like that).

Keep that bassline clean...!