Replacing floor and bulkheads in my bay boat.

My floor has some serious soft spots and needs to be replaced. I am pretty sure that my bulkheads will need replacing as well. I might as well replace my 20 year old pitted aluminum fuel tank while I have the boat tore apart as well. Has anyone out there done much fiberglass work before? I am trying to decide if I want to replace the floor with more fiber glassed wood or to replace it with something that will not rot again. Any thoughts or input?

I think a guy on youtube did a whole series on that on a bigger boat. He goes by friscoboaters garage.