No, I haven't done anything like that. My DD is like your son and we are just decided to do early admittance kindergarten. So I am afraid, I don't have any experience for you- just thoughts from a mom in a similar place- but with a different type of school.
I guess I would talk to them about the difference between his output abilities and his comprehension. I would plan at this point for early kindergarten admittance (sounds like he is ready for that but maybe not ready for first grade), supplementing at home with reading materials for him, and read aloud materials for you that are at his comprehension level and then talking with the school to see if more can be done to meet his needs. They may not be able to do much more than early admittance and possibly differentiation in the kindergarten classroom, or they maybe able to do more. But you won't know until you ask.
