Has anyone experienced back issues when packing loads? I'm only doing about an hour of hiking with a 60# pack and I seem to be developing chronic soreness in my back that lasts a week or more. I've got a kifaru frame with the regular stays. The pack is fitted well and all of the weight is on my hips, so I'm not compressing my spine vertically. Maybe pressure from the lumbar pad? It doesn't bother me when rucking and there is no immediate acute pain either. I have bulged L4 and L5s as well. I don't know for sure that it is the pack. Maybe I'm just going through a bad spell with my back. It hasn't bothered me at 30# or when I am out hunting all day.