Firelight and Infrequentflyer789
Yes, yikes! I don't think a "cold box" of the necessary size would be too difficult to find. Expensive yes; there are some pretty large reefer warehouses around but renting one out for a few months could put a considerable dent in the distribution of beef or frozen veg. Getting the temperature down to minus 50C would be a challenge (normal working temperature being minus 18-20C) and intake/exhaust another, assuming the engine would have to be working.
If the AAIB were to go the route of testing temperatures it would probably be more expedient to rig up a prefab coldstore around an existing airframe.
oh, and Brian...
JS Mills?