Thanks for digging that up for me. Unfortunately, I need -55C on the low end. Do you have any way of determining if the -40C is the hard limit of the part or if that is just as far down as they test/guarantee it for?
As far as I know, the published specifications are not hard limits, but when you go beyond the specs, then you are in unknown territory as to what might happen. I have an inquiry out to someone who might be able to give a more definitive answer. I will let you know what I find out.