Tweaked around with the awning this morning. I couldn't get the awning to slide in the slot on the tube, nor at the wall. That might be doable, but I can see would prove difficult.
At the top of the channels on the TT that the arms retract into, conveniently, there is a hole in each side, so I was able to attach a short bungee (approximately 8" long) that goes around the head on the front end of the awning. It may not be necessary, but adds some insurance and peace of mind about it staying there when on the road. I have added to my checklist when setting up and breaking down, to unhook / hook the bungee.
I figure in 2-3 years I will have to replace this awning fabric, so this fix should be fine until then. Thanks to all for your helpful comments and suggestions! Much appreciated!