Doepfer

>  I'd probably just make copy of the midi track, but route that to another channel/output for the trigger signal.  Should work, right?

Hmm... so leave it as it currently is for the gate, and also copy it to another MIDI channel, truncate all the notes of the copy so they're essentially short triggers, and use that second channel's gate output as a trigger for the ADSR envelope generator?  That's a neat idea, thanks!