I've done some thinking along similiar lines (homemade headset). Y'see,
in my setup, I just connect the radio output directly to my cochlear
implant processor, I don't need the headphones.
What I need is something to hold the microphone in place.
I did ask a couple of manfacturers of those new lightweight headsets
about it. One wouldn't do it, and one misunderstood the setup I wanted
and qouted me for the volume control (which I don't need) and the cord
that connects from the radio to the processor (which I don't need). He
didn't respond.

Anyway, I thought about using one of those computer headset, but I kinda
doubt the mike would be resistant to the noise of an airplane.

I had the idea of getting a good aviation headset and using the mike
from that to craft my own headset...maybe merge with a computer headset
for the boom arm and headband.