Keith, it may not be fashion concious but what about puting your camera bag inside a normal roller type piece of lugage. Have found Lowpro ruksack a lot cheaper than their camera ruksack and the bags are the same, it's just the liner that is differant. I would look at getting the next size up to that which fitted your camera bag so that you had room for waterproofs, flask and sarnies.
Regards Paul.