I can’t address the galvanic isolator, theres never been one at the docks I kept my boats at.
If you want Solar, figure out how much power you need to keep the batteries charged, how much sun you will get per day/week/month. Then you will have to determine how many watts of solar input you can put on the boat. Its very doable. You could have permanently installed units and portable solar panels.
Then you will have to decide what kind of panels, and controller you want. I have a 6300KW array of panels for the house. It interties to the electrical grid. I also have two 300 watt panels, 30 amp controller, and six 110AH batteries. I can run electrical equipment in my shed in all months but the mid winter months. Then I just use the 110V.
I know several in the club have solar panels installed on their boats, they would be a good source on how much 110AC power you would have to add in addition to the solar.