I would speak out for what I think was right. And persistence in doing what is right is important. But it is counterproductive to complicate things trying to change meeting schedules and procedures that are working for everyone else. I'd just get off the committee and find one that I could accommodate. Showing up is important. And there's plenty of work that needs to get done.
Please provide some specific reasons you think Rebecca isn't on the same page with your vision for the Committee.
And after that, hopefully Rebecca will reply and share her thoughts and vision.