I put on on LED lights the last time my catamaran trailer lights were giving me problems. Well worth the extra cost. LED's are sealed, they should last nearly forever, and the bolts for mounting the kind I got were stainless steel. I don't know the brand off the top of my head.

I just bought a brand new trailer for my power boat. Its supposedly (standard bulb) "sealed" lights were full of water after the first time I launched the boat. I will be converting them to LED's when they stop working.