been there, done that
My 37 center cockpit has the same light portson the front deck. They were badly crazed andapparantly a source of leak some time back.I removed the lenses, brought them to a localauto glass replacement store. They measuredand had a couple of options for plexiglas andlexan. I had to fabricate the replacement withtwo discs for each port. A larger diameter forthe on deck surface which needed to have a beveledge for fit and a smaller diameter to fit through the deck and give some strength to theunit for those heavy foredeck guys who you knowwill be walking on them. I pieced them togetherwith some clear epoxy and siliconed the rascalsin place. I went a little cheap on the thicknessof the upper piece, and will probably have toreplace sooner than I'd like, but no leaks notedyet. Yes I put a four inch solar powered ventin that forward hatch.