My kids are somewhere between bright and maybe MG and easily work 2 years above their grade level in math. One year of acceleration is not going to be enough for your kid.
If you want to test the idea get a free trial of Aleks (
http://www.aleks.com/webform/bn1-154) and see how far he can go with all the brakes removed for a few weeks. Aleks can generate reports to show the school how he does across the common core curriculum and might help you get more acceleration, but honestly... unless they are extremely flexible it is going to be tough getting him appropriately placed at school.
