Sorry if I implied that this would be anything close to a standard
battery bank. I was thinking of a bit larger add on bank. But it's
still about 200lbs of wet cells for each hour of operation, with
dimensions around 12x14x18 inches. And at that power level one should
concider 24V or more DC.

But the practice of wiring the inverter to the house side. Leaving the
engine starting batteries to start the engines is still sound advice
for a boat of most any size.