Western Canada at that, it's usually bone dry out here, though it can get up to +35 C on some hot Alberta days (that's almost human body temperature).
The rear door behind the Conductor's seat helps, on a few occasions we had all three cab doors wired open in addition to the windows.
Some guys forget that there is a door over there on these units, and checking if it was locked on unattended locomotives was a favourite 'efficiency test' for a little while.
I hate those pointless tiny mirrors, probably aren't even 8 cm tall.
Standard cabs are definitely better for switching, our 6000 series SD40RM's are probably the best I've had (they were remanufactured in the 1990s from pre Dash-2 units). The cab is a bit roomier, the seats aren't quite as worn out, and you can see forward. They even have mirrors, and of course pull just as well as a SD40-2, I think they would outpull a SD60 and be at least the equal of a DC traction SD70.