Hi there, I work for bmi upa \t Manchester and we are also very experienced in assisting passengers with extra requirements. We had a love chap fly with just last week, he too had autism. He needed to be on first to familiarise himself with the aircraft, layout and seatbelts, he also wanted to take photographs of each stage to help him explain his trip to his family! All of this was done so he could be relaxed and confident and we made sure he was looked after appropriately and not obviously as the last thing I'm sure you want is people looking at you all the time. We made sure that this gentleman was "passed" discreetly between check in, gate and crew.
If you do go to Syracuse then will you be picked up in New York? I would suggest this as your best option because you can get a point to point flight and not have to transfer, which means that you woud have to collect your bag in the US.
I too advise you to avoid Locosts, they don't usually provide any extra help or assistance.