As stated by Ianfca, “…it is a case of what your personal budget will allow to include any additional luxuries.”
True, but if they’re not authorised then they’re not insured.
On a total loss claim, Motability will replace the vehicle on a like-for-like basis, including authorised extras. If they’re not authorised, they will only replace the vehicle as per the (current equivalent) standard specification vehicle – as is the case for a ‘normal’ PCH contract.
You cannot expect a third-party insurer, in this case RSAM, to insure unauthorised equipment at zero cost.