I am not at all sure that the cold is killing these people. For those of you with brake temperature gauges, pay attention to them in flight... Some of them are quite warm, even after a LONG time at altitude. I suspect it has to do with the proximity of all the hydraulic lines and pumps and whatnot that tends to populate the main gear wells.
Prolonged exposure above 30,000 feet without supplemental o2 is guaranteed fatal... and most of these long haul jets are well above 35000 feet by the time its over. However, interestingly I see temps of 45-50 degree C frequently on the brake temp gauges long into cruise flight. I think it actually might be rather hot in the main gear wells.
If you climb into the nose gear however, I think that would reside somewhere between TAT and SAT (I would guess -30 degrees C or so) and even for a relatively short flight at a lower altitude like 25000 feet, you would have a reduced ability to shiver to stay warm (not enough O2 to do the vigorous exercise that is shivering is) so you would be susceptable to hypothermia much quicker than normal.
Cheers
Wino