I'm a linux guy, where possible. I did use the stand-alone kindleunpack.py to split the dual-format mobi.
Just as a teaser, I ran a test epub, along the lines of what Hitch suggested, but very, very, bare bones, through kindlegen (command line version 2.9) and got somewhat more complicated results. I need to dig deeper into these results, but note that this was the first time I passed an epub through kindlegen that contained any pixel-dimension coding at all. The results are confusing. Stay tuned.
For now, gn8 and sleep well.
Albert