An audax organiser once told me that people had approached him to try to have the TCR style event they had entered registered as an audax and he had had said no because these events are races.
I've also realised that even if there's a way of doing it, having to submit DIY controls for every 80km or so throughout a ~2200km route is probably ride admin I could happily do without... I think I'll stop pursuing this idea :)
An audax organiser once told me that people had approached him to try to have the TCR style event they had entered registered as an audax and he had had said no because these events are races.