If you want something temporary to block out the light which also will keep out the cold and sun too?
I use
van sized windshield sun shades. They fix exactly in the windows of an RV and slide right up under the day night shades without having to tape or velcro them.
They come in all kinds of colors and designs so it doesn't look too tacky from the outside like the plain silver ones do. Walmart's carry a good selection of them.
I bought the ones with palm trees on them. I use them to block out the hot summer sun when in Florida. I slip them under the day/night shades on all the windows on the sun side. Works Great!
http://www.walmart.com/search/search-ng.do?ic=16_0&Find=Find&search_query=windshield+sun+shades&Find=Find&search_constraint=0&_be_spellv2=on