Here it is with a 30W flood light with color changing option. I had to tape the background on the tank at the top than tape the bottom to the wall and adjust the led so the light would hit the wall at the right angle. I like it so far but i think i could have gone with a 20w led.
Looks like a good balance between the aquarium lights and the background lights. That is what I find most difficult with high-light tanks. You might want to keep the floodlight at a greater distance so the light does not drop off at the corners.
When you get bored of the look, I would like to see this landscape with a light-blue flood light at the top, you also need to reverse the background's angle.
Maybe use a bit yellower (lower Kelvin temp) bulb and aim it a bit lower to still have the sun rise effect, but have more darkened upper corners, it would look even more so! Then just add a little Pride Rock in there
EDIT: Oh, forgot you got a color changing light, perfect to find that yellow hue!