That looks awesome! Do for see any issues with the laminated image and the heat.Personally I didn't like the available subject (pictures) on the cling on backgrounds I could find. My other issue was that I wanted to cover three sides of my 40 gallon breeder tank. This meant I needed to order different sizes for the sides and then contend with whether or not the picture would blend continually around the sides.
I went online and found a high resolution picture of a background I liked and copied it on a thumb drive. Took it down to a local print shop and had them size it to the exact size I wanted then laminate it with a matte finish. (you do not want it shiny) I then bought some black foam poster board which can be found in school supplies of your local Walmart. While I used black you could use whatever color works for you. I cut it 1/8 inch wider in the width so that it wedges in very snug and stays with no tape. The laminated picture I tape to the back glass on the inside. You will want to do this first then place the foam poster board side panels in last.
I'm in the process of cleaning the tank at the moment but here's a picture. I'll try and remember to update it once I get everything back in.