Perhaps you weren't aware, but rape is already legal, provided the victim is a minor and the rape is done by a medical professional at the behest of the minor's parents or the state. In fact, this goes on every day - every time someone wants to "prove" that a minor was a victim of sexual assault, without regard to the minor's feelings about the matter.

(Yes, of course, the "professionals" use only their hands and various objects, but "rape" is really about sexual violation, rather than the specific means.)

Of course, it could become widespread in a hurry - I seem to recall a few years ago that there was a pilot program in which ALL elementary school girls in one town were given gynocological examinations - whether they wanted them or not. The girls had been given consent forms to have their parents sign them - but when the day came for the exams, it made no difference whether the parents had consented or not. The purported purpose of the program was (ironically enough) to protect girls from sexual abuse by identifying girls who had been sexually active - and so these "child advocates" sexually abused girls to prevent the sexual abuse of girls. Fortunately, widespread outrage in the community stopped that program shortly after it started, but the fact that it could even be considered demonstrates the lengths to which fanatics will go in order to force their will on others.