Interesting concept, something I'm occasionally drawn to. I think it works better from further back, so there is more of the boards/fence than the view of the rubble. That way you could get the fence sharper and the image would be about the contrast between the barrier and the scene behind it rather than being about the scene with the barrier just used as a frame. If the latter is what you want, then less of the boards/fence would be better. I also don't think vignettes work that well on a surface with relatively little detail like this one. Just my two cents ...