You definitely don't need max Ethical, I got it with a Widow that kept toeing the line and I was juuuust barely on the ethical side of the halfway mark when Clarmont tried to break up with me. (I remember I had to wait to do a murder on my personal issue storyline, finishing it JUST in time to not get arrested, so I think I was even back into Immoral when Sayra talked to me.)
Also, to get Mrs White's nod, you just need to have filled half of the Rebel approval bar (which is the "max" you can have at this point, or thereabouts).
I think you can still figure out the secret and continue the storyline with all the other requirements, and not having 50% Rebel approval just gives you a lot of Clarmont and Sayra rivalry (Mrs White gets mad at you but you still piece it together). This is probably for the allying with Gisette's family route, but maybe you can still ally with the rebels anyway...? It doesn't take away from their friendship/romance/respect, so maybe it's still possible.