Craig,
If your surveyor has flagged the need for an ELCI breaker, then you'll need one to get insurance. The Blue Seas people have a nice writeup on installing one, but there are others that make them (less expensive than Blue Sea?). You can install one in the main panel ONLY if you can get from your shore power connector to the main panel with a 10' max piece of cable. Otherwise you'll need a box for the ELCI located closer to the power connector. This 10' limit is like the old limit on the distance from the connector to the former main breaker (with reverse polarity indication). I had to redo a trawler several years ago as the connector was in the aft cabin and the main panel was at the helm - too long a run.
Hey, it's only money...