Tufts is a hard one to tell. I have a friend who was well outside the top 10% of his high school class but got in RD. It’s really a crapshoot but as far as I can tell you have a good shot.
To the OP: If it’s any consolation, one thing an admissions director from Cornell said 4 years ago has stuck with me: fully 75% of their applicants are more than qualified to be admitted and do well, they just don’t have the room. Brown was my D’s first love as well (& those are hard to shake in any iteration!), but after a good talk with her college counselor, who objectively weighed her chances but also encouraged her to “go for it,” she decided to apply ED1 to Tufts, got in, and has never looked back. A good friend of hers at the same high-school was deferred from Brown ED1 with superhuman stats (she was admitted in the regular round), but jeez, it’s hard to imagine who they are accepting early. Mostly athletic recruits and $$ people? One thing my D concluded, is that no school is perfect, but there are many schools that one can be happy at, I mean let’s face it – no one is a sure thing at any of the Ivies/Stanford anymore, unless you gave a ton of $, or are an athletic recruit. Their acceptance rate is just otherworldly low. Those who get into Harvard get dissed by Columbia, and on and on. Tufts is considered similar to Brown in terms of its student body composition, lifestyle, and campus atmosphere. You have a good chance at ED2 at Tufts and grab it if you get in! Brown’s yield is so high, you’d have to be at the top of their list to get an acceptance after deferral.
I think there is (especially on the east coast) a continuing lingering attitude toward Tufts as being the “safety” for Ivy rejects; that it stands in the looming shadows of Harvard and MIT, and hasn’t yet escaped its poor cousin status. And it’s therefore less desirable I would say, based on the last 5-10 years especially, that this attitude has almost completely been replaced by respect for Tufts, its admissions process, the education it confers, and the success of its graduates. The school could do more to have an alumni and donor presence, and the dorms are a disgrace for the amount of money you pay, but the education and opportunities have been first rate so far.