Based on your post, I’m guessing that you’re in Massachusetts? If you’re within commuting distance of Boston, both Newman (coed in Back Bay) and Woodward (girls, in Quincy, but across from the train station so girls commute from all the greater Boston area, including the north shore) will take late applications from strong applicants. They are both fantastic schools that don’t get nearly the respect they should.
It’s honestly not worth borrowing trouble, though: in a week, you’ll know about the other schools you applied to. Only worry about a Plan B if you need it 