I don't think your focus is misplaced at all.

Does the school accept that your son is GT?

Do they recognize 2E issues, generally speaking? So that they can imagine a GT child who is also behind in some areas?

If the answer is no to either of these questions, your job will be much harder. I don't know if that helps, but it's what I think of right off the bat. There may be some educating involved for you...

Kriston