Water heater came from the factory with the "convenience package". It was mounted under the V-berth, centerline, in the compartment just aft of the anchor locker.
Islander's did not have A/C as a factory option. Sailfish did.
I installed a 6,500-BTU reverse cycle A/C (Mermaid Marine Air) under the aft end of the galley unit.
Neither the Islander or the Sailfish have room for an installed generator. Honda EU2000i works fine if you need power away from the dock.
Brian