I'd suggest eliminating the connector altogether. Drill out the center, run new wires through the hole, and use one of the "rubber in a pressure can" products that's sold in TV ads to form a water tight seal. Quick, simple, and permanent, and it eliminates a possible source of resistance and corrosion. Then drill a drain hole in the bottom of the headlight housing to give the water that will inevitably accumulate somewhere to go!
Jerry