I researched this topic back in my youth, and I wanted to share my thoughts.
It’s not so clear from the Rambam and S”A that women aren’t allowed to learn Torah Shebal Peh. Even though the S”A says that one who teaches his daughter Torah it’s as if he taught her “tiflus” (tiflus being something negative), the S”A also say that women receive sechar for learning it! Now if the S”A was saying that it is assur, the S”A wouldn’t have said they get a reward for doing it. The S”A just says it can’t be taught to them which I understand to mean that it is not allowed to be imposed on them, however if they learn it by choice, then they receive reward.
One also has to factor in (based on the S”A and the Rama) that a woman does not have a chiyuv to learn Torah which has no practical application, and has a chiyuv to learn Torah that has practical application (halachah, mussar, Tanach [Gemara in Megilah says that the only nevu’os that were recorded were those who’s messages are meant for all generations, therefore Nach is practical], etc…). It’s a positive thing to learn the areas which have no practical application (the S”A says they receive reward), it’s better than wasting time, but it’s not a chiyuv.
Based on this, I think there are 4 criteria that need to be met for women to learn Gemara:
1) They have to want to do it.
2) It has to be for lishmah reasons, not feminist reasons.
3) They need a teacher to guide them in the right way to learn Gemara.
4) It can’t come at the expense of learning those areas of Torah that are a chiyuv for them to learn, but it can only come at the expense of things that are reshus (learning secular subjects, going shopping, etc…).