I agree with you in principle on abortion, for the most part.
I do accept the life of the mother exception, which you probably don't.
I understand, although do not agree with, the rape exception (Incest makes no sense, it was either consenual and thus would not fall under iape, or its rape and so would.) I still don't agree with it, but I can understand why an otherwise pro-life person would accept that exception, and I wouldn't discount a candidate by default on it (Eliminating 95% of abortions is a heck of a lot better than not eliminating any.)
As you said, we're short on choices this year. Honestly, while I wouldn't really call him pro-life, Gary Johnson is pro-life compared to Obama or Romney. I'm not supporting him because of an amazing abortion view, but the right to life committe backed him for gov. In spite of the fact that he carries the label "Pro-choice" he did sign every bill the right to life committe asked him to sign, and he opposes Roe v Wade.