Classic Beam Rot

Hello Fellow Adventurers and Wharram Sailors, Just had to post here, sorry about the topic. It seems no matter how big a beam you can make, the fungi will make short work of it, especially encased in an epoxy/fiberglass shell. The water gets in somehow and doesn't escape, the wood is food for the fungus and deteriorates rapidly. My mast crossbeam, which is the shortest and most easily replaced, has fallen foul of rot. I'm replacing it with an aluminum I beam capped with the proper profile of the Narai MKIV central crossbeams, this part made in pressure treated wood. Quite a job plopped right in the middle of other mods. There is a necessity to strip the sheathing off the remaining beams and sound them and deal with them with an antifungal treatment or replacement. Has anyone done this, and how has the result lasted? My aluminum powder coated items have done well in almost ten years. I begin to wonder about the stem and sternpost, those keel problems I noticed a couple of years ago when I hauled out. Big pieces of wood aren't so stout when they become food for the rot buggers. I'm blogging on sailblogs.com, search for kaimusailing, or look under "K" and look for Kaimu as a boat name. Fair Winds and Following Seas, Andy and the Kaimu Crew