i am stuck with the same problem. i'm going to try removing the foam part of the hump. that way the bag will feel more "in the middle". i was thinking to use that space to hold a video camera for a helmet cam.
i just did it and it took me less than a minute. it will work nicely. i like to use a separate back-protector anyway.
i just did it and it took me less than a minute. it will work nicely. i like to use a separate back-protector anyway.