This is a long shot, but I have some heavy custom flats up in the Bronx.
The smallest is 8' 8", the largest is 9' 10, they're staggered to fit around a riser. They're all 1/2" MDF with routed panels, laminated 8' down from the top. We also had to extend them at the last minute, so they're scabbed up like nobody's business.
You want 'em, you can have 'em.