I would agree with the accommodations you've listed. Perhaps you've seen these OCR resources, which may be useful for advocacy purposes:

Dear Colleague letter and Resource Guide on 504s for ADHD: http://www2.ed.gov/about/offices/list/ocr/letters/colleague-201607-504-adhd.pdf

Parent guidance on above letter: https://www2.ed.gov/about/offices/list/ocr/docs/dcl-know-rights-201607-504.pdf

(same info in a couple of other languages) http://www.parentcenterhub.org/repo...nd-resource-guide-on-students-with-adhd/

Note in particular language on page 12 of the resource guide regarding excessive effort as indication of educational impact:

"Someone with ADHD may achieve a high level of academic success but may nevertheless be substantially limited in a major life activity due to his or her impairment because of the additional time or effort he or she must spend to read, write, or learn compared to others.44 In OCR’s investigative experience, school districts sometimes rely on a student’s average, or better-than- average, grade point average (GPA) and make inappropriate decisions."

...pronounced like the long vowel and first letter of the alphabet...