I was investigating getting a tank adaptor to fill my CNG tanks directly from an LPG Gas Station - the subject of numerous threads on the forum. I now know someone who will make them for you in San Diego and can ship them to you. The CNG adaptor is as per the tech notes description. If you are interested in getting one of these please get in touch with Justin:
harbordocs@yahoo.com
619.977.8167
Cost: $119.85 plus shipping.
(Harbor Docs is a marine tech unit with a shop at Sunroad Marina on Harbor Island, San Diego)