Chris, that would be a tough one. Thinking it out in my head it seems like you would indeed need a separate function for each light color. If the class lights were all shown out of one lens, as on some E and F units, then I think one output would be fine and use a tri-color LED. But with three separate lenses for class lights you would need three separate LEDs.
Right now I don't think there is a button that cycles through the colors, but that would be an easy thing for Ring to add. The bigger issue is how are you going to wire up the LEDs and are you okay with taking up 3 function outputs doing so. That would leave you with three....one for headlight, one for ditchlights, and one for rear. Should work out fine that way, unless you were planning on doing anything else (strobe, beacon, groundlights, etc).
-Kevin