I don’t have experience with admissions to tippy tops, but I did think of something that might help. Have you talked with parents/students at the high school? Ours lacks good math teachers for Calc BC and beyond. The word is that the kids better be ready to teach themselves at that level. That wouldn’t have worked well for my student who likes math but is not super gifted in it.
My other thought is that if the current accelerated math is challenging when surrounded by 8th grade classes, it might be highly stressful when taken with honors or AP in other subjects.