I do think if we are to approach this in any reasonable manner the first thing has to be accurate and unbiased recording and reporting.
How can recording be accurate and unbiased without a definition of what being a woman means? When collecting data for any sort of research all parties have to understand what is meant by all of the terms being used, and agree to use them in the same way.
We have seen what happens on here when people are working to entirely subjective definitions based on things like ‘presentation’ or shared values. Clearly neither of these things would stand up in court (fortunately), so fixed legal definitions need to be found, to cover what is meant by ‘male’, ‘female’, people of either sex who have transitioned to the other gender and people of either sex who identify as the other gender. That way, decisions about things like prison accommodation, access to safe spaces and so on could be made in ways that take account of the differences between those groups, and research into medical and social science disciplines would be far more accurate and unbiased than at present.
On a day to day basis doing so should make little or no difference to the lives of transpeople - I’m not suggesting that there should be any need to declare anything, and the right to privacy should be protected. But on forms, in court (when relevant), or for other official purposes, would it not make sense to make the distinctions clear?
Thought this might amuse some of you!

Of course I should have said "the artificially constructed penis" instead of using "your". Sorry to have let the cat out of the bag 