yup, was just projecting from that time with my bags. As you say, guess it doesnt matter what setup you have, it doesnt mean you will or won't have extra room.
Like the idea of a nylon knapsack, there are many out there now that are super light and pack down to practically nothing. In fact my wife has one that has held up well for a few years now and I never even thought of using it (partly cuz I hate wearing one while riding, but for bulky stuff that wasnt heavy it would be fine, especially if just for not a long time)