"there are no way that I can find to split the outputs of lead-vox and harmonies":
I have no Play Electric, but I have the following tip:
1.Set SETUP/OUTPUT to MONO.
2.You probably have to set SETUP/LEAD_MUTE to On.
3.In VOCAL FX, you probably have to turn off all effects blocks except for Harmony (ie Double, Delay, Reverb, Hardtune, Transducer, uMod).
4.Use GUITAR OUT
Dry lead vocal will be sent via the left XLR output. Dry harmony sounds will be sent via the right XLR output.