Why do you feel he won't get the recognition needed to support his additional behaviour needs?
At this stage, he doesn't fit in the box labelled 'school' and you've said there are issues with other relationships.
Schools follow a square peg fits in a square hole type policy, they have no additional back up for a child who is a different shaped 'peg' without accessing legislation which should give them extra people or resources to do the job.
So, you then end up with the different shaped 'peg' on a special or specific needs register because its the only way schools know how to access information on doing something outside of the expected format
It may be more helpful to you to think of your son as having an individual need (indeed this is what my ds school calls their policy when children need things to be done a little differently to the 'norm')
So, the starting point for you needs to be a professional assessment of his individual need, what triggers it - the behaviour support teacher ds saw at one time called it ABC - what happens before the behaviour (can it be distracted from for example), the behaviour itself (what role do adults play during the behaviour) and the conclusion (how does your ds feel when the behaviour is over)
Then, they move onto whether your ds can modify his own behaviour (in which case they use reward charts etc) or whether the environment needs to be modified (allowing to go to a quieter space etc)
From what you have written, you may need to look at a different school as the present one doesn't sound like its supporting ds or you.
Unfortunately without being able to identify the additional individual need he has, schools often can't provide any tailored support.
What are they actually doing to support him in school?