Actually those whole generator thing does open up lots of possibilities......
Does anyone make decent weather resistant home audio amplifers and equipment? If you can run 110V off a generator, why not run 110V equipment? Lets face it, car audio speakers are not designed for "loudspeaker" duty. Its easy to find stuff on the home audio front designed for that kind of abuse. Then you eliminate all the 12V shortcomings (that is until the new higher volt standard hits the car market).....
I would highly recommend a generator in the boat. With my system (6k watts total) I can crank the system for about 30-40 min and then the batteries are completely dead. I am running 3 optima blue tops to the system and one exclusively for the boat systems so I can still start the boat once I drain the stereo batteries. On the next boat, I will definitely have a generator to keep the batteries up. Once the batteries are drained, it takes forever to bring them back up to start over. If I am not cranking the system, but just listening to it, I can get it to play for about 3 hours on a full charge on the current configuration.