One thing you might want to consider is making the pack with a second pocket, to hold a cell phone/random stuff, so that the pack isn't just always sitting there. (That may eventually draw attention: "Why do you carry a purse AND a pocket pack?" Using the pack for a cell phone or other item would give the pack a "cover story".)
You say you're working with leather - leather may require an interfacing. (Or, you may want to branch out into fabric. :) I have a Threads past issue article on purses that recommends these for heavyweight bags:
-FormFlex heavyweight fusible interfacing (stacked in layers, if necessary) - FishmansFabrics.com
-Timtex - more heavyweight than FormFlex? - 1/8" thick and nonfusible (TimtexStore.com)
-Stitch N Shape - available as a nonfusible, fusible on one side, or fusible on both sides. Can be shaped with steam after you stitch it together. (RNKDistributing.com)
...and there are most likely leather-specific interfacings out there, too.
Hope that helps you somewhat! I look forward to seeing these in fine department stores everywhere.
