Gregory Palisade Plus

For the most part, I am in love with Gregory packs. They are very high quality. After a number of years, my pack doesn't show any signs of wear whatsoever. I particularily like the pocket on the back of the pack - the "older" Gregory's like mine didn't come with hydration systems, so I put my big hydration system in the big pocket along with my rainpants and map. The V-compression straps on the side of the pack are wonderful. The sleeping bag compartment would be better with a U-shaped zipper, but I get by fine by simply not using a compression sack and shoving my sleeping bag in with the aid of the lower vertical compression/sleeping pad straps.

However, I have one problem with my pack when I am carrying a heavier load (above ~25 pounds): the hipbelt tends to slide down, and in order to keep it up I have to make it very tight. However, it still slips down, and when it does, it puts excessive pressure on my butt-muscles. Having this excessive pressure on my rear then causes severe pain within a half-mile. This problem became so bad during my last backpacking trip that I carried most of the weight on my shoulders the last day, which was much less than ideal. I then had to stop frequently to rest my shoulders. I think that my torso is shorter than the minimum torso size allowable for this pack. I bought a size medium and I think that I really need a size small; this may be the root of the problem. Has anyone else had this problem? Any suggestions? My funds are low, so I don't want to have to buy a new pack if I can avoid it.