Don't know about backpacks, buy I used to use a CTC-1 to good effect. It worked nicely with my AF rigged with rails and monitor on the back, plus of course all the usual great array of pockets for batteries, mics, cables, etc.
This backpack has a picture of a rigged out AF100: http://www.portabrace.com/products/camcorder-cases/camera-rigs/786-rig-4bksrk. Might be a bit overkill. It also depends on if you are looking for a backpack, shoulder bag, or rolling bag. I'm guessing you are looking for a backpack. I use the Lowepro Vertex AW300 with my AF100 on rails with lens and shotgun mic. The camera sits in the bag in profile so it is as flat as possible. It has room to spare for other lenses and accessories. I can also take this backpack on planes which is a big plus.
