FWIW, My 1986 41' Hatteras Came from the factory with a 50A, 240V shore power service which was just about right for two A/C's and all electric appliances. Unfortunately the engineers at Hatteras assumed that no one away from the dock would actually drop an anchor and cook! She came equipped with an 8kw (30A, 240V) genset. Then, to make matters worse, I installed a 240V watermaker. Life seemed to be a constant rerun of the "Green Acres" episode where Eva Gabor had to carefully add the numbers on her electrical cords in the kitchen to keep from blowing fuses.
When we finally declared our 8.5kw Onan close enough to death to be rid of it, we upgraded to a 12kw and life was good again! Last I heard, the Onan's three cylinder Kubota was still merrily providing power for an Amish woodshop.
For me, the moral of the story is that too much power isn't nearly as much trouble as too little.