We took some of the aluminum bubble insulation and put it between the window and the Day/Night shade. I fitted the bubble insulation tightly to the edges of the window. Didn't use tape or anything else, just cut it close and pressed it into the edge of the windows. Keeps out almost all of the light. Also put some up in the skylight in the shower. You can remove the inside part, put insulation over the dome and put it back up on the celing. I have an insulation square pushed up into the toilet room vent to keep light out from there.
BC