I know exactly what you're talking about. I use my pack a bit differently than most. The lab I work for does sensory ecology work, and we often have to haul RV AGM batteries into the mountains to power playback speakers. I often haul 2 batteries at a time, which comes out to a little over 130 pounds. Because the load shelf sits so low, the bottom-inside edge of the lower battery falls right at the top of my sacrum. For the first time in many trips of hauling that load in the last couple years, I actually rubbed a fair amount of skin off my lower back because of how the load shelf rides. The load puts a lot of weight on the bottom third of the belt because of the ride height. I haven't tried it yet, but I believe you can change the ride height of the load shelf by tightening the straps running down the back of the frame and into the top of the shelf. This may not work if the load you are carrying is too wide for the strap adjustment, as you are essentially pulling some of the shelf up the back of the frame, but otherwise this might be a solution for you.