This is the result of said experimentation. I just jammed a few photographs together and painted over areas, adding some rudimentary effects and whatnot to try and establish a theme. It's very rough around the edges, but it only took me around an hour to put together, so it's a fast method of visualisation.
I didn't really want to use this approach to generate concepts, but I've spent too long fumbling around with no result. At the very least, this has given me something to work with.
Here's another experimentation. Figure I might try some lighter ones tomorrow, to balance out the rather dark tones in both these mash-ups.