As luck would have it though, this weekend I stumbled across the Lowepro Photo Traveler 150. It is a SLR system camera bag designed to hold a body and several lenses/accessories in a backpack style. I prefer the backpack since it evenly distributes the weight and I feel I can hike further that way.
Anyhow, it is quite roomy and very adjustable with many dividers and lots of places to attach them. Here's a quick video I did showcasing the new bag loaded up with a K1. (sorry for the shaky cam!)