No, no, and no. At least use as much of an aluminum (6061) plate about 1/4 inch (assuming you are backing a good fiberglass deck) as you can to spread out the forces. Use a good bedding compound and still use large fender washers on the fasteners unless the plate is quite thick.
"I don't think there'll be a return journey Mr. Frodo". Samwise Gamgee
For what it's worth, I used 1/2" G10 for the backing plate on the windlass I installed last summer. Extremely strong under compression forces and never corrodes. I made it more of a "foredeck" backing plate and included the chain stopper.