Can I play devil's advocate and propose a variation to the cooler box which is actually a variation to mod #3 - I'm currently on #5, a cold finger.
Using the tripod mount, fix a strip of 3mm aluminium strap to the camera base, cut to size to fit one or two TEC modules with heatsinks and fans. The camera is then set in a smaller box, putting the cooling in contact with the body of the camera, improving thermal resistance, dispensing with volumes of air. It would be necessary to exclude moisture from the box, of course.
If you were concerned about cooling directly to the camera base, a gap of 0.1mm would be adequate, separating the strap from the base. A few holes tapped to fix the heatsink/s.
