Just curious: What's wrong with carrying a weighted backpack for training? It seems that doing so kills two birds with one stone (NOT THAT I GO AROUND KILLING BIRDS).?
Doesn't carrying the backpack one plans to use for the actual hike get the body used to the weight and the feel of it??
And really, who cares what people think if they see you walking with the pack down the main street in broad daylight? Maybe they'll think you are homeless and throw you a few coins - whilst telling you to keep moving. ;-)
Ken.