Could work, but you may have to subpoena the AG person to testify. Then you run into the legal argument that the AG office is independent of civil actions and cannot testify on your behalf. They usually only send an amacus curiae brief or witness to explain to the jury what the law says. I don't think they can testify on your behalf.
The letter may be admissible, but you'd need an affidavit. Again, you get the argument that an affidavit consists of sworn testimony. Since that testimony is designed to be used against your opponent, you are back to square one. Just my opinion, maybe someone has gone through this and has a way around this argument.