Thanks. Some years ago, my wife "tricked" me into an easy, short loop hike (it was a loop, but neither short nor easy). I carried the already packed shoulder bag and load I normally carry as you described, short/quick trips to vehicle, etc. The nice small pack remained, empty, in the car. Found out after a considerable amount of ups and downs on a trail, that I totally agree with what you said: "it isn't a pack".
Still, it looks like quite an efficient solution for those short, quick transitions. Certainly much better than the shoulder bag I used previously.
Thanks again.