The Halcyon plates pictured above don't have many wing position options....
You could go with a soft plate that come in sizes..sm, md lg. Soprassub and Hollis make them. But they are $250ish and come with a deluxe style harness.
Or.....use something like
this. They can't be more than 13" in length judging by the grommets. I am eyeing this on myself. The 'quick draw' rings suck btw. I have them on a Zeagle Express Tech and the waist strap wanders. I added tri-glides and problem solved.
I am assuming you want the weight of the SS plate. These options don't help in that regard.
ETA on sale
today