Replacing Seat Backs

The wood in the back of my fishing seats is getting soft. The upolstery is still fine so I'd just like to pull the seats apart, cut a new piece of wood, and then put the seats back together. Could this be as easy as it sounds? I know I have to coat the wood with epoxy or fiberglass. Epoxy the best? Also is a conventional staple gun strong enough to drive the staples through the epoxy? I assume they make stainless staples that should be used. Are these strong enough to go through the epoxy or will a lot of them bend?

you don't need to coat the wood just use treated plywood and you have another 10 years out of them , by then the fabric will fall off, staple gun is fine, no boat manufacturers don't use stainless just normal staples they will last for many years

Thanks- I guess I was making too big a job of this. These seats have lasted 20 yrs so any repair will probably outlast the boat.