Dray ... taking your ideas a little further. For the curtain rod idea, a rod with the rings with clips on them. That would give you the ability to take a picture when you do not have a hanging sleeve. About design walls .... mine is black polar fleece, 7-1/2ft x 12ft. I have had it for a couple years now. Really like it and have absolutely no regrets ... other than it could always be bigger!
I actually have some smaller portable ones 2ftx4ft that get used too. Yes, the threads show, but a quick run over with a lint brush/roller cleans them off easy enough. I decided I'd sooner have that, than the threads on the white .... and the white getting grubby!