Baz,
How are the headrest covers actually attached? Is it just a cover with foam in it that slips over or is it actually attached? If it is not firmly attached then it wouldnt be serving the intention of the standard and they have reason to request it to be fixed. Even though there is no way your head could physically whiplash over it. Perhaps you can find someones seats to borrow for the inspection?
My RX7 seats are border line, if measured from the bottom of the bucket they are 855, if measured from the bottom of the back rest section they are closer to 750mm. The diagram in the ADR is not the clearest to know where to measure from.
The thing i have thought about is modifying the mounting location of the bracket that connects the seat back to the bottom, so the seat back is mounted higher thus leaving a gap at the bottom that can be filled with a lumber support. Perhaps you could discuss that with your trimmer. Only problem is that one side is mounted with a bolt to pivot on.
Are the fittings for the tonneau cover screwed on? Can you just unscrew them.
Dont be intimidated by him going through every ADR, your car has been built by a professional to comply with them. An expert inspector wouldnt have to read through every ADR, they should have such a good knowlege that they just have to occasionally look up specific numbers. I reckon he is just busy and is giving you an excuse. If i were you i would just wait for the report and try not to get him upset.
Makes you wish you were building a hot rod. They have life so easy, yet try to make out these are "just kit cars" and are heaps easier then hot rods.
I wonder how the clubbie guys are going with all this. Has your Engineer got anyone else going through or did you keep in touch with others doing the brake test?