Thanks for all the suggestions. To answer a few:

I already use an external frame Kelty pack for long trips where I have to carry more than 40 pounds or have to take climbing gear, etc. The Kelty simply is over-kill for 5-7 day trips.

Setting the bear cannister upright on top the sleeping bag takes up entirly all the pack volume in a men's medium pack let alone a women's small pack. Plus the long rigid edge is very uncomfortable because most of the pack then cannot contour to your back. A bear cannister full of food must be centered or it will tilt you. The room left on either side simply is not the right shape for pots, stove, and other rigid objects. I have done this before when I only needed my bivy sack, but once I need a tent it does not work.

Taping D-rings on a bear cannister adds to weight. Since I spent $$$ to get a light bear cannister, it kind of defeats the purpose. The NPS regulators also can technically cite you for altering the design - and this invalidates the "approval". Now I do not know if any ranger would be that picky, but I suspect there are a few overzealous ones out there.

Those of you who use medium to large men's packs, just take a look at a women's small and see just how little space they have! I have spent my lifetime wearing ill-fitting packs simply to get capacity! I do not think we small women who solo backpack are enough of a market to intice manufacturers to design us something specific. I think they assume some big guy with a monstor pack will go with us to carry our bear cannister or the other gear our bear cannister replaces! Only in our dreams!

A bear cannister loaded with food is about 15 pounds. Some theoretically good solutions often just do not work because with that weight it must be centered, stable and as close to your center of gravity as possible to comfortably carry. The rigidity is also a real problem. The only really comfortable soultion I have found so far is to strap it to the exteder bar on my Kelty. But my Kelty with extender bar weighs nearly 6 pounds. Without an extender bar, the cannister tends to flop forward and bonk you on the head! The lighter and smaller new external frame packs have a bent small extender (supposedly to give you head room), that tends to set the bear cannister farther back, hence, away from your center of gravity.

It looks like I will have to go custom or specialty to get a suitable pack. Thanks for the links to those sites. I already own 4 packs - amazing how we accumulate stuff that we think is going to work then does not!