Well it works. Shuts down the camera at 61C or 142 F.

How do I know this you may ask.....

I did a time lapse of a thunderstorm blowing up w/ my 2 battery grip and FPS on the video set to .5 FPS (1 every 2 seconds thanks to magic lantern )

It consumed about the equivalent of 1 battery. And the total record time was 50 minutes though the video time was 50 seconds (30fps when played)

Any ideas on cooling the body/sensor? I can certainly start with a "chilled" body so 10C/50F or so put the lens on and fire it up before I take it outside to the hot/humid I would think the sensor would heat up fast enough to prevent condensation.

I could strap on a couple of cold packs to the back of the body once the shooting starts.