Hi Glenn,
I wish I could be more help, I am a Ski Patroller, but all of our communications are done on a "standard" portable radio, far from anything as modern as an HT. :wink: When we have to switch channels we have to deglove etc.
A speakermic is the only advice I'd have to offer, but I suspect your in-helmet headsets trump that even still. However, looking at it from a HAM perspective, you might be able to find a handheld radio system that has functionality built into a speakermic (channel changing and volume control) but that's just a thought. Perhaps there are others that will be able to provide some helpful insight, otherwise, I'd agree with akroeze and would suggest spending more time speaking with dealers.
Sorry I wasn't more helpful. Good luck finding a solution.
-skibum