chances for average looking female rep

If you don't have a high level of self confidence, then don't waste your time in ortho sales.
As for looks, it's ability that matters. Looks might get you in the door a bit easier with new relationships, but after a few meetings, the surgeons want a performer, not eye candy. You'll get along better with the OR staff if they perceive you as a professional rather than someone trying to get by on their appearance.