Quick floatplane water start at LUDD, C&D:
To answer my earlier question, the tweaked LUDD gets its data from:
D:\Flight Simulator\Official\OneStore\microsoft-bushtrip-sanjuan\Scenery\bushtrip-sanjuan\Scenery\San Juan.bgl
If you look at the nearby W55, and 0W0, in the same dock, they both use this:
D:\Flight Simulator\Official\OneStore\fs-base-genericairports\scenery\0101\APX15150.bgl
LUDD was definitely tweaked as its part of the above bushstrip, which is first party content. Further evidence of it being an answer that is not very accurate.
It’s the first one I have ever seen, and for all I know its the only one. I wish there was a way to get LNM to only show custom airports, as that would make it so much easier to pick them out.