I'm sure someone else with more experience will chime in soon, but I have seen the Iowa Accelaration Scale mentioned frequently and wondered if you or your school has access to it? It just seems like it might be a good way to present/evaluate a grade skip in a more objective way.

Just wondering, what is it that you see in your DD that lets you know school isn't working? Does she do stuff at home that you could use to make a portfolio?