The elementary school has referred DS10 to the middle/high school for acceleration. Although I have been tempted to leave him in 5th grade, becauuuuuuuuuse, he found a friend. A kid who is 2 years younger, grade skipped up to 5th grade. He could have been skipped further but his parents declined. It gets better, the boy is super nice, his family is wonderful, and we're neighbors. In a district with <100 students per grade, we have a peer friend! They are hilarious together! They each have just enough sense of competition to egg each other on - exactly what my unmotivated DS10 needs, and they both struggle with perfectionism but express it in opposite ways.
They will still ride the bus together even if/when DS10 is accelerated. His family is coming over for supper tomorrow to plan logistics of getting them together afterschool.
DS10 had been opposed to acceleration until he realized he wouldn't lose the friendship. Their bus ride is an hour long. They sit together and quiz each other! State capitals! Periodic table! Archaic vocabulary! That plus regular play time will help DS10 with social skills and social stress.