I would imagine that there would be lots of FC470s in various states of assembly in the San Diego area, where you could make a template from existing aluminum floorboards.
If that is the case, you could simply get a couple of sheets of marine mahogany plywood (min 5/8" thick, 3/4" even better) and make your own floor boards. Use a few coats of a high quality marine epoxy sealant, and the floorboards will be fine for decades.
Admittedly, 3/4" marine plywood floorboards would weigh a fair bit more than zodiac's corrugated aluminum floor boards, but they would also be much more rigid, strong & versatile.
http://www.westsystem.com/ss/epoxy-resins-and-hardeners