Welcome to the forum, cyrus.
When I was in that situation a few years ago, I prepared some materials - reading materials, notes and questions - that I faxed* to the student, with clear instructions about what she was to read before the lesson and what not. I had my copy of the sheets in front of me when the lesson started, and it was not very different from a normal one-to-one, except that we could not see each other.
The school had said that I must send them a lesson plan. I sent an outline plan, but made it clear that I might well deviate from this, as I often did in one-to-one lessons. As it happened, I hardly followed the lesson plan at all, and used less than half of the materials I had sent. Having the materials, and knowing that the student had hers, enabled me to have something to fall back on if (useful) sidetracks seemed to be leading us too far astray.
*You could just email today.