As said before the only winning move is not to play. You either straight up don't allow it or you quit. It wouldn't be allowed if the women on the team all quit in solidarity.

Since it's women's sports it's really a women's issue and I think rather than blaming the trans-women for taking advantage of these obvious loopholes (it is basically cheating) a large share of the blame needs to be put on the women who allowed this situation to begin in the first place.

Don't play games, don't fuck around, just give the ultimatum. Either you don't allow trans-women to compete on the women's team, or else I will resign. Enough women do that and the nonsense ends.

You don't have a choice anyway in the long term. If this is allowed more and more trans-women will dominate women's sports and it will essentially become a trans-women league by default and you'll be edged out anyway. Why not just quit of your own accord now and not bother to deal with that nonsense?