Must it be a bar?
As a general principle, protein + moisture = bacteria chow. It's trying to keep the protein and moisture separate that's a problem.
I'm thinking you could pack dried fruit, nuts, granola -- maybe made with soy flakes for some protein. You can pack whey powder or soy protein powder and mix it with water along the way.
My favorite bar recipe:
http://www.foodnetwork.com/food/reci..._31336,00.html
I've made it without eggs (increase the water) and without sugar and they're okay that way but not as tasty. If they can be hermetically sealed they should last a while.
This is a tough problem...