I have used the 8.5-inch ones for 10 years with both incandescent and LED lights and never had a significant problem. I painted the outside black and distressed them w/ forest green. There are holes at the base to allow heat to escape. If you are using LED lights then place electric tape over the holes to block any stray light and rain drops. I will also use these pointing upward which will collect water - Drilling a 3/16" hole in the base near the socket will help drain any water that collects and using one of these gaskets along with a GFCI just in case. Heavy rain will trip the breaker on the ones pointing upward. Then again, somewhere among the hundreds of lights, I use for Halloween or the 10's of thousand of lights I use at Christmas, one of them always trips the GFI during heavy rain. Use Silicon spray or WD40 on the inside to make it shine and repel water.Sounds like you are looking for something like this.
Woods 300-Watt 6 ft. 18/2 SJTW Incandescent Brooder Clamp Work Light and Heat Lamp with 10 in. Reflector and Bulb Guard 166 - The Home Depot