bocephas, I think you should consider your notebook to be rather "disposable" due to the harsh environment it'll have to endure. Don't buy an expensive one, and opt for the "An elephant shit on my laptop. Please replace it.
" type warranty.
As careful as you'll be to not get sand grain in it, you will
get dust in it, and the bearings in the fans will eventually fail. The hard drive will probably be alright for the duration that you're there.
Dust may even find it's way in between the membranes of the keypad under the keys, possibly inhibiting contact of some of the keys.
When you do choose a laptop, consider figuring out a way to filter the intake air for the fan vents. Obviously too much of a restriction will be counterproductive (to the point of being downright detrimental
). I'm thinking like a thin layer of gauze...breatheable, but can catch dust, and be replaced cheaply on the fly.
Perhaps a laptop cooler will help.
Install a free fan utily program. That way, you can shut the fans right off and monitor your CPU & GPU temps, and turn them on only when you really need them.
And then finally, I recommend a a felt lined aluminum case for the laptop instead of a bag. Dust is less likely to get in, and you could even run a bead of silicone caulk along the lip of the case and let it dry so it forms a gasket-seal when you close it. Things won't be able to smack into it, etc.
I sure hope you find something good. Document it's use throughout your tour with pictures of it being used in a harsh environment. -Maybe when you get back the manufacturer will give you a new super-system if you send in the photos for promo purposes!
(Thank you, bmwrob. We're lucky you came along to straighten everyone up.