If you really want overkill, how about one of these on each side of the boat, powered up by a breaker? Run a length of boat cable from the fuse box to each light. Each light will even have it's own fuse! You can't get safer than that.
I have one, powered up by the instruments breaker. Each instrument is then run off an individual fuse. Makes wiring tidy and easy.
Blue Sea Systems 12 Circuit with Negative Bus with Cover from Wholesale Marine