Replacing plywood floor

[Barracuda]

Just found a section of plywood at the forward right hand side of my 1995 AS that is soaking wet, as I lifted the carpet to replace it with vinyl plank.
It looks like there has been a leak for some time as I managed to push a screwdriver right through. There is a section break in the plywood just aft of the damaged area, so I should be able to remove the for'd section.
My question is how easy is it to do this. I did note there were large countersunk screw/bolts, which I presume secure the plywood to the frame. Any advice would be much appreciated.

[Lumatic]

How big is the damage?

[Barracuda]

It's an area that extends maybe 6" in from the shell and maybe 3' long

[Lumatic]

That is a fairly small area. Short of replacing the whole section there are 2 alterrnatives:
1. Cut out damaged area. Scab in a replacement piece of plywood (screw in a backing piece and then screw in the new piece to the backing piece.
2. If the old floor is still intact coat it with penetrating liquid epoxy such as Rot Doctor