I was lucky. The 15 year old young man I buddy boxed had his dad with him. He stood in front of us and would sign to JJ what he needed to know. This worked pretty well for a student as the plane was always over his dads head. JJ was lost a year after that so I don't know how it would have worked when he soloed. Sorry if this dosn't help you but it helps me to talk about him.
David