Hey Paddy, I work for a company that builds assistive technology software for people with physical, vision, communication and reading impairments. One of the primary apps I work on is an app for non-verbal people who use this to provide a voice - many people who use this app are on the autism spectrum, from both ends of the scale.
When I performed research I found that for the AAC project I was working on the primary users split naturally into family and professionals, and those pre-purchase, early on their journey or more advanced users. There was also the need to capture the user, but (and I'm sure you're aware of this), there is a well known saying "If you've met one person with autism, you've met one person with autism".
In a roundabout way I just want to echo Ashlea's comment - your research will uncover insights that will help guide you in forming these archetypes to help move you forward. If it helps my process was the following - understanding what business know (or don't know), use that knowledge (extensive in my case) - I created proto personas to make sure we were on the same page, and I used these to help source people to speak to, to get better understanding of the users and their needs. This in turn led to the personas I mentioned above.