I would consider replacing the bulkhead with same thickness FIBERGLASS not wood, for the simple reason that plastic just CAN'T rot the same way, ever. Places like McMaster and Grainger sell it up to an inch thick, theonly question is whether they have sheets big enough to replace the whole bulkhead in one piece. And then, apply veneer or other facing over it to make it look proper.
If you can't find plastic, I'd use an epoxy penetrant or something similar to (again) make sure that problem simply never can happen again.
I wonder if anyone makes zirc fittings for chainplate deck mounts?
On the bright side--that's still a cheap price for a Sabre!