Reading this, I predicted that he'd sleep straight through! 
He sounds a bit like DS, who is younger. Confirmed sensory processing issues as well as reduced executive function (which is the bit around organising and planning). Sleep has been a nightmare from the start. And he copes remarkably well with less sleep than I would think is needed but then does crash every now and again like he needs to catch up. I am always grateful as everything else improves at same time. Usually the behaviour deterioration as a result of tiredness doesn't happen overnight. It takes a while to happen so we don't fully realise what's happening until he gets his 12 hours at some point.
I think with children like these the effort to help them with sleep is unfortunately never ending, but you have to keep trying. So you can accept that they're not going to sleep like their peers but where you can, help to figure out better solution. In your case, I'd consider letting him sleep past 10 at least some of the time as a way to let him catch up on his sleep.
[and for record, if anyone suggests its parental "fault", I assure you, that's bollocks. We, hilariously, have children at opposite ends of the spectrum. DS who struggles with sleep, overall clearly needs a bit less sleep than average and was 8 before he slept through and then there's DD who has always been a good sleeper and age 5 still routinely requires 11-12 hours. She didn't sleep through until she was 3 but her "wake ups" involved a bit of crying, 30 seconds of back patting and that was it. Parents of her friends are gobsmacked when I tell them I need her asleep before 8 during term time and I still then have to wake her at 7:30 for school.... ]