[I33]

Gary,
Thanks for your comments. The breakers for the 120 circuits are on hand, just not installed yet. They are going to be placed just behind the entry connectors, not at the electrical panel, as I have a long run between entry and panel.

I also plan on adding the galvanic isolators, I just didn't put them on the drawing for simplicity's sake.

I want to stay with the twin 30-amp shore power cables as I will have at least one 30a most places. I have one 120v air conditioner and will therefore always have at least some air available. When we have 50a, 240v available we will be able to run both ACs.

I agree that many marinas have both L1 & L2 tied (incorrectly) to the same leg on a 50a service, but don't see that as a danger to the 240v air conditioner. In that instance, there would be zero volts between L1 and L2, and the motor could not be damaged by that. Sure there would be 120v from either L1 or L2 to ground, but the motor winding is not tied to ground. The same situation with Neutral as there is no Neutral connection on the air conditioner, just L1, L2 and safety Ground.