So I thought I'd share this with you in case anyone wanted to give it a go. I have recently painted some headlights up and rather than let them get condensation build up from no covers. I thought they needed modifying as running an LED bulb you cant use the original covers. So i improvised, I found that a rainwater coupling is around the same size as the inner diameter of the original cap. So i made a 20mm extension and plastic welded it on. Using some spare caps from the main beam which fit perfectly onto these. They fit perfectly in the car too.
Any cooling issues in term of durability of the LED bulb just the fan is blowing onto a flat surface with no real air movement