If you need school's accomodations and behavior

management support, you need to let school know, so that your son can get IEP or at least 504 plan.
Hold back 1-2 grades and supplement with high level classes or activities that matches his interests at out of school time.
I went through your problem when my kid was young. I wish i hold his grade back for 1-2 years.
The GPA in high school is mainly reflect self discipline and management skill not IQs. Ave. IQ + High EQ+ organization skill +self discipline has much higher success rate than very high IQ + ADD.