Nick, I have the same problem as you--long femurs, poor ankle flexibility--down to the pinching.
It takes a really long time, and you just have to keep working at it. Stretch your calves and ankles all the time. My ankle flexibility has improved somewhat from regular Olympic lifting, but not as much as it would have had I been as diligent about stretching them as I should. When it comes to the pinching, I just kind of alternately keep pushing at it, do some dynamic stretches against it, massage the area a little, and go back to pushing at it. Originally I would feel a "crack" (this sounds worse than it is, there's no pain), and the pinching feeling would stop and I'd gain a few more degrees of mobility. This cracking has diminished as my ankles have gotten more flexible--I'm guessing as I keep working at the flexiblity/mobility whatever restrictions that are going on there are loosening up.