My son is a HS senior who was diagnosed in grade 8. After a disastrous freshman year at the local HS, we moved him to an out-of-district public sped school (draws from a number of SD's in the area). He is still brilliant and unmotivated, but should be graduating HS in June with a regular diploma and, hopefully, going to community college.
His program is an 8:1:1 and his services are extended times for tests and counselling, almost every day if he needs it. The teachers in his school WANT to work with these kids and are inordinately patient and giving. Yes, the work is toned down so m son did not learn physics and chemistry at the same level as in the regular HS, but honestly it's no matter - he does not plan to pursue a future that involves either of those.
In your situation, I would ask for regular counseling with someone who is experienced with Aspies and I would sit down and meet with all of his teachers at the beginning of the school year, provide them with some (brief) literature about AS, let them know they can contact you any time. If he is as bad as my son about HW, I would ask for some kind of HW sheet to be sent you weekly or whenever.
And now the opinion that I have evolved to over more than a dozen years in the school system - mainstreaming is not always for the best. My son spent grade 9 at the local school because his dad was not willing to accept that the HS life was NOT for him. I had wanted to send him to this other school in grade 9. My husband changed his mind the day the school counselor called and told us that a very nice young girl had told her that she sat down next to my son at lunch and he said to her: "Why do you want to commit social suicide by sitting near a pariah like me?" The girl was so upset she went to a counselor because she thought my son might hurt himself. He has NEVER been suicidal, thankfully.
Anyway, at this school he has PEERS, he has FRIENDS! He goes to the movies and iceskating with a group of kids and now that he drives (and quite well), he is even more popular. This past weekend, a friend of his from this school who is now in college studying culinary arts came down with a friend to help us prepare a catering order. The brother of another friend he met at this school came to help. I wish he had been in this kind of environment for a longer period.
This would never have happened at the local school. My daughter is there now and I see how it would have been for him. My daughter is kind but many kids are not and even the ones who are not overtly cruel just ignore kids like my son.
Sorry to prattle on, but I just feel it is so crucial that Aspie kids have PEERS. So many people talk about being around neurotypical kids and that is important, too, but if your school can offer you a "Circle of Friends" group consisting of peers and select NT kids, that might be the best service you can get. Some of the kids at my son's school are not Aspie but have other issues like Tourette's, bipolar, severe Obsessive Compulsive Disorder (OCD), panic disorders, etc. He is learning to deal with all types of people and their issues.
Good luck.