I was thinking about your gearskin on a frame idea last night. The normal gearskins close in sort of a taco shape. You might want to try it as more of a sandwich. Where the back piece comes completly off. With the frame you might have problems getting the bottom to fully compress. If anything else it will help you to get gear out of the bottom easier without undoing the whole pack.
Just a thought I had while thinking up way to pack my gearskin when it finally comes.