Well lets just say moisture is coming in through a pinhole leak in the fiberglass... What could I do to coat the entire thing, preferably without siliconing the entire housing?

 

I used aluminum tape on my motorcycle headlight, no fog so far, but I do live in a desert.

 

Do you want it not to fog up... drill another hole in the back somewhere "smart" & the air can circulate.

 

But wouldn't drilling another hole in it just allow moisture to build up that much easier?

 

No, I tried sealing everything up tighter than a nuns... I tried sealing things up really well. Having airflow helped my headlights & when I get around to it I'm sure it will help air out the tails on the odd occasion they get condensation.
Just drill the hole the same size as the one existing & on the opposite side that still has air flow between them.

 

Yeah my minis are just hooked into the h4 tab part on mine, no seal at all and no fog. Fog builds up when it is sealed and you get some moisture in there. When the capsule heats up, it evaporates the water and it condenses on the cooler lens. With some airflow, this gives the water vapor an escape.

 

hey if i were you, i would be happy. went from a normal headlight, to a fog light.. Lucky...... :P