How about enabling Solo Override (Shift+Solo) on the audio track(s) for the drums? Then the solo state of the MIDI track(s) determines whether you hear the synth. I could be missing something, but it seems to me that would solve the problem (until the Bakers get to it - kind of sticky wicket, because they'd have to read the drum map, and manage audio track solo states based on output port assignments, and keep up with changes).
For cases where there's only one MIDI and audio track (mixing done in the synth's GUI), just grouping the solo buttons should do the trick. I do this with hardware synths all the time since they don't "know" they're connected.