I wouldn't bother wasting time writing a letter. Actually, the research is NOT in your favor regarding preschool. Part of my psych degree involved doing a practicum at Stanford's Bing Nursery school, which is all play based. At the time, people were paying $10,000 in preschool tuition there. We had to review all of the research that said play based was the way to go. Of course, probably most of that research is based on neurotypical kids!
We ended up going with Montessori for preschool. Here's my review:
http://teachingmybabytoread.blog.com/2011/06/16/montessori/
