I never unplug my trailer lights when unloading / loading the boat. But my bulbs don’t last but a few months. I use my boat about 3 times a week. I have the submersible type that is vented at the bottom. Bought from Wal-mart. I guess they have sprung a leak. One of the lights terminals (where the bulb plugs in) is rusted out. The other one is fine but the bulbs in it burn out just as fast as the corroded one. I’ve double checked the housing for cracks and checked the gaskets. I even added some grease in the terminals for corrosion. But the bulbs only last a month or two. Anyone else have this problem? Must I unplug the lights?