I have rigged a lot of boats, and often use sealed LED marker lights for under-gunnel lighting. Here are some that I use often:
https://www.amazon.com/gp/product/B073TBY6H9
The amber light is easy on the eyes, but still bright enough to make them useful at night. Keep in mind, this is for function, not show, as we do a lot of night fishing. For rod locker and storage area lighting, I have been favoring similar sealed LED units in white:
https://www.amazon.com/LEDVillage-Marker-Lights-Trailer-Trucks/dp/B073TFJXM8/
Personally, I don't like many of the other colors for functional lighting, but they look pretty neat if just for show.
There are many LED light modules that you can get for very little money. I've been using these little buttons a lot. They are made for trailers, and work very well on boats. They are small, and can be tucked away, but make a lot of light for their size:
https://www.amazon.com/dp/B0B58X7DNY
For LED lighting, I use a lot of TINNED copper wire. Tinned wire is very durable in a saltwater environment:
https://www.amazon.com/gp/product/B01N0A16X2
This wire carries a lot more current that many wires that are supposedly higher gauge. Very good wire for most low-level LED applications. For high intensity lighting, you need to size up according to wattage and wire run.
I hope this is helpful.