Perfect isn't achievable? Why?
I think the reason you say this is that you are still wedded to the idea that some way must be found to allow males to compete in all-female events. Why is that? Why do you think some way has to be found? Why is the preference of these males accorded absolute priority over anything the females might want, or what might benefit the females?
Imagine the death of the soul for the best females, constantly seeing males beat them even if the males' times are disallowed for medals. Imagine the heartbreak of training with these males. Imagine constantly having it shoved in your face that no matter what you do you can't actually come first, even if you get the gold medal.
Handicapping? That isn't going to be any better. The objective of a handicapper is to achieve a complete dead heat at the end of a race. The idea that some competitors are handicapped while others stand outside the handicapping system is bizarre. The arguments, the challenges, the days in court, I can barely imagine. (Not least, the lawsuits from the males who insist that they are really, truly, actually female in their souls and that it's discrimination to treat them differently in any way at all.) You want to run "female" events on the basis of two starting lines, one for females and one for males, and hope that the female group and the male group can arrive at the finish line together? In the name of the all-holy FSM, why?
The idea that we can just give this a go and see what happens, and then decide whether we like the result is insane. What about the women and girls whose athletics careers will be completely wrecked in the time it takes to make this decision? Why this obsession with putting female sports at risk to find some way where you still let males compete in female events? What is the thinking behind this? Oh yes, more "the males must have what they want and to hell with the females." You are doing the equivalent of giving in to the owner of a very slightly modified F1 car who wants to compete in F3 races, thinking, well how do we accommodate this, rather than saying no, that's against the rules, go away.
And please stop using this term cis-women. It's grossly, grossly offensive to many women. We are women. The word is taken. Men can't have it. We are not a subset of ourselves. We are women.
Leaving aside the small number of genuine DSD conundrums (I'm mainly thinking CAIS here, where the competitor is genuinely a woman but has a definite but slight edge due to her SRY chromosome - Semenya is simply male and that should have been recognised and addressed long ago) the perfect solution is simply to exclude genetically male people (and any female who has ever taken exogenous testosterone) from female events.
Women's athletics (like rape crisis centres, prisons, schoolgirl summer camps and yes, sanitary facilities) are not a validation mechanism for males with identity issues, and they should never have been allowed to become so. If there is some sort of problem with males competing in the male classes, then find another solution. I personally don't see what the problem is other than educating males that there are many many ways to be a male and to be a man and that excluding people because they don't perform masculinity in the usually accepted way is discriminatory and phobic.
Funny how it's the women who want to retain their female-only spaces who are constantly traduced as "transphobic", but the men whose behaviour (allegedly) makes it impossible for transwomen to use male facilities get a free pass. Oh, sorry, not funny. Entirely predictable.