I don't know if this will help but a few month ago maybe one year some guy from Illinois an engineer as much as I can remember had replaced the floor in his boat with some stuff from this site http://www.closedcellfoams.com/polyethylene.html I kept this because I have an inflatable floor that I'm not too happy with and I was thinking getting a hard one ( just dreaming ) at the same time depending of you boat configuration you'll be able to get a hard wood floor or alufloor from boatstogo.com but depends on availability.
Good luck
I wrote a pretty detailed post on this a while back, I did mine in HDPE and they work great. NOT lighter than wood but better by far. Aluminum is lightest but big $$ to work something up custom.
