Hi Chris

,
try (again) the Morganpark people in Hamburg (as you already have done…) - they delivered several M3W Super Drys & at least 1 Roadster 3.7 in Satin/Matt silver metallic already afaik…
But expect maintenance / care to be a real pain in the a** (at least)!
Swizöl developed a series of special care products for satin finishes, also Petzold´s as far as i´m informed…
Good luck!

P.S.: i know what you´re thinking about...