If you know you ride on your pubic rami more than on your ischial tuberosities, you probably want to look at something with a very wide and padded nose and a very gradual transition from "sit" to nose. The rami are sharp and thin, while the tuberosities are thick and blunt and heavily built up. The width at the back won't really matter because with that much anterior pelvic tilt your hip joint simply can't extend that far anyway and I just can't see the hamstring getting into trouble.
There is a very good split-nose saddle that I've suggested to a few of my clients who ride aero:
http://www.bikewagon.com/ISM-Adamo-C...-p8176886.html They seem to like it. It is a little wider than what you are considering, but it is certainly designed more for rami than ischial tuberosities.
Don't forget a woman's pubic rami are at a different angle than a man's (theirs angle backwards more than ours) so you may need to monkey around with shape and nose width quite a bit before you find perfection, so don't give up!