OK, wow, just wow!! You folks are amazing. Truely. I just got back from a week long trip around the Albemarle and mostly staying away from the internet. I am pretty confident in being able to reseal the ports. I like butyl tape too. I am now convinced leave the fixed light teak trim alone. I will remove the crazed plexi and replace and reseal with something (recommendations for sealer on these?) Without first removing to inspect, mine looks like the plexi is grooved and the sealer is a gasket inserted in the groove, and the screws are set through the groove. Perhaps is is just a very neat sealer job.
In my fervid imagination, I was hoping to take all the ports out, put up the new paneling, cut it out of the ports including the fixed light after install with an edge trimmer, reinstall the ports and the light. Install the outside corner trim that holds the steaming birth headliner with screws as before and sail away. That fixed light is beautiful. I love the narrow trim of the existing teak face against my painted paneling, and don't want to change it, but I don't have the skills or time to rip that out and remanufacture all that. The teak frame seems salvageable, so I think I will sand and oil and leave it alone.
Formica:
Jim, I think that might be a bit of genius.
Once I get all the port lights out, perhaps I can remove the rot and delaminated sections of teak paneling (already painted white). I can fill if necessary locally, but cover all with Formica. It is thin, but stiffer than teak veneer, and will not detract from the beauty of the delicate fixed light frame. Templating around the fixed light window trim, will be slow and painstaking, but perhaps they are both the same so I will not have to do it twice. It might work. Attaching the outside corner molding will have to be done with adhesives rather than screws. That might make some of the headliners very difficult to remove in the future. This method it predicated on the top edge of the panel being a straight "factory edge". The cutting will be on the bottom and covered by the outside corner molding. For me formica is harder to cut cleanly, so I need that smooth edge.
My existing paneling is butt-jointed in 3 spots. Since the cabin top flares slightly that butt would open slightly at the bottom -- the original installer knew that and cut is perfectly. I think Formica can be cut with a knife using an overlap as a straight edge, so that I can make those butts as nice as before.
My wife, says "Oh no, don't go all perfectionist on it -- you will end up ripping it all out and redoing it all, and we will not be able to sail for months" ahhh the words of the bard were never truer, "to sail or fix the sailboat that is the question!"