Hardipanel works great against the elements, but is somewhat easy to put a hole through or crack with impact if there's no firm sheathing behind it or if your studs are far apart. It can also be a bit heavy, since it's made out of concrete. I found this stuff called Ondura at Lowes that I'm going to try the next time I re-side a blind (
http://ondura.com/). It's composite, comes in brown, and looks like it would be pretty durable (it's roofing). I'm not sure if it will warp in the heat or not, though. Not your ordinary blind material, but maybe a good one.