Have you ever heard of a pelican case? its a plastic case thats very durable (water proof, dust proof, and it provides great anti-shock resistance)
Check them out at
http://www.pelican.com they have a lot of great videos at their website
if you want something for just the body i would recommend a case this size (1200, but there are smaller and larger cases available) , it would also accommodate a lens attached to the body. I do quite a bit of backpacking myself and i plan to purchase one of these to throw in my pack. hope this helps...
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Canon 40D + 70-200mm f/2.8L IS + 50mm f/1.8
Manfrotto 055CX3 + 496RC2
www.thomaslowe.com