Quick update, just in case someone else with an Eleuthera finds this thread one-day. I've contacted Kent-Marine, Indel Webasto Marine
, Beard Marine
, MultiTech, and Titan Marine Air, but none have been able to help so far. Everyone is asking for a model number and manufacturer, which doesn't seem to exist.
I also contacted rubber companies... no luck.
I did hear back from Fountaine Pajot and they provided me with the dimensions of the gasket
... so maybe I'm making some progress.