YS DS8 will be SSA in math this year also. We have had to agree to essentially switch his entire classroom placement and at times during the week have him take classes with older students (which could actually have benefits since he is also an advanced reader) to make this work. It is still an imperfect match and his schedule will be a bit of a mess.

Really, scheduling is up to the school. You really should not have to worry about that. What material are you concerned about him missing?