>>Listen to Casey, he's a pro. <<
Can I show this to Mrs. Casey? She needs a good belly laugh.

But seriously, thanks for the nice words. I enjoy helping when I can.

Gluing on a ply reinforcing plate, scuff the plastic to break the glaze. Coarse steel wool would do nicely and it conforms better than sandpaper. It won't hurt to wipe the area down with a CLEAN cloth and rubbing alcohol. A fuel-soaked surface does not provide the optimal glue joint.

I still think I would use a flexible adhesive: I use Miracle Glue from Charlie's Hobbies in Tampa. I'm not sure what it really is, he gets it private labeled. PFM from Hobby Lobby is very similar, or Shoe Goo available at WallyWorld. Epoxy or Polyurethane(Gorilla Glue) would also work, but if the plastic flexes too much that joint could peel. PU would be the lightest choice.

I haven't seen your floats, but I would first consider one ply plate, long enough to take both the front and rear mounts, and extending an inch or so past the front mount to spread the load. It'll act as a "spine" to the float. If you are using some sort of pilow-blocks on top of the floats to attach the struts, glue them in place, too.