I wrestled with the same problem a while ago. In the end I used an old K fender on my F, and bobbed it at the front. Yes I lost the rolled edge, but fitting the tail light hid most of that and also added rigidity. It's on the second page of my build thread.
Incidentally, the fender I used was from a much earlier K than my F, and whilst the side mount holes didn't line up there was much more area on the sides to re-drill than the one in your pic. It looks like the Carpy one is made to fit, but does not replicate the dimensions of the original.