Do ahead and document it. My Father's Grand mother was full Cherokee. But there is no documents, and no way to document it. My Father was born at home, as were his Brothers, and sisters, and I don't believe there is even a birth certificate. Maybe a blood test. Not interested in it now. Proud of it, but no interest in documenting it. There is a girl out here that is full blood, but was adopted as a young girl, by a white family, and raised as white. But when she reached out to the local tribes, instead of welcoming her, and helping her, they called her an apple. Red on the outside, and white on the inside. So she just , said OK, I reached out, and that is what I got, so be it. Good luck.
Wayne