How did this thread get this long without me?
90 degree? Heck, I frequently see a 105 degree requirement with the Ruud HID lights I use.
As I see it, the requirement ends as soon as you leave the enclosure. In practice, this means either a box on the opposite side of the wall, or a splice where the mounting meets the pole.
This has to be a requirement completely ignored by the trade, as the folks at Graybar have absolutely no idea what wire to supply. Inquiries typically get an answer involving a couple thousands feet of wire, with a price of $5/ft.
It seems that the electrical parts houses are completely ignorant of the high-temp appliance wire sold at the local hardware store or appliance repair shop. This is the stuff covered with woven fiberglass. 0.75/ft, cut to length, any color you want.