More than one BCC owner has made similar inquiries (see: Portlight maintenance? - #13 by MCilenti).
One marine product supplier in the US did have a stock of laminated glass on hand. More recent reports were that that stock had been exhausted.
You should be able to find a glass business that makes laminated glass to custom size.
We were sailing Zygote down the Malacca Strait on a voyage to Singapore when we heard one of her portlights crack. No trouble finding a business to make laminated glass. Deal is to measure the final thickness of the glass in one of your portlights, then work out what two sheets of glass could be laminated together to produce that final thickness.
We now have a small number of spare laminated lights, because all glass professionals work with rectangular sheets and then cut the final product. As always, carrying a spare or three guarantees you will not need them!
If you’re keen, you could make your own laminated glass, it seems: