Use Velcro to attach your own black-out lining to your curtain panels < this is gonna change how I do curtains forever! This way I can use whatever curtains I love, and Paulo can get is pitch black room!
Change out your normal curtains for burlap ones for the fall. Who cares that seams show, that's even better. heck even glue on some spiders :) There even the possibility of no-sew if you have those curtain clips from IKEA.