Good luck!
We only just managed to get a grade advancement for our daughter (for the fifth grade instead of 4th). We were able to, because she completed the 4th grade curriculum of home school (along with other outside advanced classes) concurrently with her 3rd grade brick-n-mortar classroom. We had to go all the way to the Asst Superintendent, because the principal just couldn't fathom how a child would need a grade advancement.
(If I hear "yes, but her age is...." one more time..!)
We had Woodcock Johnson scores showing achievement through GE12-13 across the board and other tests. The principal just couldn't see scores and her other outside work. It took going to the Asst Superintendent (with the principal's suggestion actually...).
No idea what is going to happen this year.
Good luck.
