NM, here is the best I've gotten to so far.  We'll call it a study in realistic simulation being hard and overfitting being too easy.  Somewhat ironically, it is your original algorithm with different parameters and basically only one (subtle) change.

http://pastebin.com/YD6bYzyP

This beats "similar optimization approaches" for my few attempts at a hand-rolled re-target, but I could probably score better with some more time spent there.  I'm curious to see if anyone can beat it, as well.

Let me know what you think.