Art:
Thank you for being the voice of reason here.
It sounds like you've been walking on this particular path well before me. I've seen some decent Husqvarna hammerguns that would work (16s and very light) and I have seen other very light French game guns (Damon Petrik for one) that would be right in the ball park. The Europeans seem to have settled on the 16-gauge for many of the same reasons that I'm a fan and built their guns accordingly.
Unfortunately... my bias tends to lean me towards the American and then the English stuff and I'm on the trail of another Brit as I write this. Light British 12s fascinate me I fear.
Time will tell however.
Impressive hammers Mr. Pickens, and used on quail and ruffies no less! Very neat.
My version of the sidelever...
A converted-pinfire Lang.