Interesting (in a good way) colors! Combined with the highlights on the beams, the effect really makes me think about the shot -- is it real? is it a toy?
Apart from the color, I like the geometry of the pipe chase and your idea of filling the interior of the arch with the defocused greenery.
In a perfect world, perhaps you could have moved back a smidge to reduce the relative size of the blurred greenery within the archway's frame -- or even moved forward to eliminate it altogether, emphasizing the hillside's diagonal. I would also like to see a version with the utility line cloned out and the utility pole at the left cropped away to clean up the composition.
Very interesting concept, though. I'd be interested to see some more shots usuing your night-for-day technique.