did you mount the number plate on the black plastic back plate? or directly to the body?I am running traditional black plates in NSW, they are both 254mm (w) X 134mm (h) and fit perfectly.
I remember going through the same ordeal. Tesla sales rep was good and provided as much information as possible and checked with the support teams.
Like others, I had to take delivery of my M3 with standard plates, then got to the local Service NSW and pick up my plates, grit my teeth, cross my fingers and hope the plates fit.