Thanks, that's why I had assumed I would have to put in lifting rings before the cunning plan of using the spar pins as lifting points.
Perhaps I should rephrase the question:
If you had to locate a lifting ring at the rear of the aircraft, where would be the best point?
My thinking is a) options are always good and it could be that it is easier to drop the aircraft into the water and unfold the wings once the aircraft is in, as my boat has a full-beam (5.5m) swim platform, from which to work from, we just need to make sure the platform itself is wider than the wing-root to make the operation reasonably safe as you can slide the fuselage up and down the side of the yacht to help unfold.
b) For short transits such as in the Bahamas or the Florida Keys, it could be easier to raft (tied to the side of the yacht with floats still in the water) the kitfox parallel to the hull of the boat with wings folded so the engine is better protected (rear of aircraft due to weight of the wings would raise the nose), though in addition to being secured over the wingbox, it would need lines fore and aft to ensure it does not try and twist against the hull. At this point, I'm thinking a bridle running from the front two float legs should secure the front of the aircraft and make sure the nose stays high.
All really interesting stuff and actually started to think this idea might not be as daft as it sounds!