My middle school was miles away from the high school, and I just reported to the resource room for math or worked on it independently (having a class was more fun, but I've always preferred working independently on something interesting than being bored). In addition, I started taking college courses my freshman year of high school and was still able to play sports and have a full high school experience (and have a nice start on my bachelor's degree). My high school simply counted the high school-level courses I had taken towards the graduation requirements (not that having a diploma would have mattered, as I was already partway through college when I graduated). Perhaps this would be an option that the high school would consider...
