You need to first start by determining the running watts of each of your electricity usages. Then determine the number of hours that each of them will run each day. Add all the watt-hours together to find out how many watt-hours of battery you will need. remember that batteries generally can be charged to only 80 percent of capacity and shouldn’t ever be discharged below 20 %. This means that your batteries need to have 40 % more capacity than you use.
Lithium iron (not ion) batteries last far better than lead acid for long term use. If you can run your boat off the generator while you are charging the batteries, you can subtract off the hours that the batteries are charging.
Food luck
That was my idea to run the generator in the morning while underway and then use battery power overnight while anchored. I plan on running up and down the Tn river a few hundred miles for a few months.