Trailer lights if installed correctly and not messed up by mistakes have a good life. I have had 6 or 7 cat trailers over the past 20 years and once I get the lights the way I like them I never have a problem. Though I sail in salt water I never dip my cat trailers in the water. A well designed cat trailer has mounts for lights that protect them from being broken. Spray lubricate in the vehicle connection and if necessary grease the light bulb contact points.