Not that I know of. I'll watch this thread. It would be great if there was.
There is a hardwood specialty place in Belgrade Montana that might be able to order it. They do not have it in stock.
I do think it's worth questioning Okoume as an appropriate choice. It is super light which makes it a good choice for racing hulls of any kind.
It is perhaps not as strong as for instance, Meranti Hydrotech. Sapele is the most beautiful but the most dense too (heavy) and the most expensive.
For bottom panels on river dories I would not choose plywood of any kind. I like honeycomb core for the bottom, good plywood and boat building boards (ash, white oak, fir, port orford cedar, maybe spruce) above the bottom, sometimes with and sometimes without a fiberglass skin. But for me, for the bottom panel, always honeycomb core fiberglass. I'm just sayin. I don't write no rules or laws.