Not interested in getting into an argument, it was explained to me as follows for the Patrol:
200kg or less towball weight does not effect GVM
250kg or less towball weight less 150kg GVM
300kg or less towball weight less 220kg GVM
350kg or less towball weight less 290kg GVM
The 200kg is built it as standard: Note that the posted reductions don’t match the actual weight, they are graduated.
Edit: don’t take my word for this, check with the relevant authorities.