Many Thanks to JohnN and Malpaso for their invaluable input and pictures.
Obviously you both know what you are talking about. I'm going to try one out and perhaps copy some of your modifications. I know it's not part of a modular system but I'm thinking about how I might adapt it to carry along on a several night backpack trip. I am always frustrated by the need to access some items without removing the backpack.

Again Thanks
Jon Davis