I have a 5 led flashlight that uses two AA batteries and have used it for hours and it is still going strong on original batteries. I have a 3 led forehead light that uses three AAA batteries and those batteries have lasted over three years of accasional use. So I'm thinking that instead of investing in pretty expensive marine led units I will use individual battery powered units placed where ever I need them.
Since you are not using the lights very often or for very long, you might find that some stick on units with internal batteries will provide the lighting you need over the settee area and keep what you have over the bunks for night reading. It would save a lot of money for other projects,