The only bulbs I've found that work in enclosures without overheating and failing are a design that's probably 90% aluminum heatsink by weight and over 50% by volume, with a relatively small dome diffuser on top. I couldn't find a US distributor, so bought a box direct from the manufacturer on Alibaba. They were $20+ per bulb even from the factory, so not cheap. Beyond the crazy cooling, they have a thermal shutoff feature to prevent failure if they get too hot.