Surname is Clifton!
I like James. It's my uncles name but he doesn't for whatever reason. He likes Carter Lee but Lee is my daughter from a previous relationships middle name and I think it'd be weird for siblings to have the same middle name.
Since Carter is really common I'd go for something less common so that it's less likely he'd encounter anyone with his exact first and middle name. So no James, Michael, Joseph, David, Alexander.
Quoting Mama Kat:" Surname is Clifton!"
Carter Allen Clifton
Carter James Clifton