this is for Ontario, Canada, where it is legal.Yeah... if only it were California legal!
VC 4853 would be the only way to make it CA legal.
V C Section 4853 Devices in Lieu of Plates
VC 4852 defines the size and lettering requirements.
V C Section 4852 Size of Plates
I don't know of anyone who managed to get the DMV
to do this for them. (I researched this back in 2009...
and ended up with a front plate in the end, to comply
with the VC and make daily driving more enjoyable.)
VC 4850(a) states that you are issued two license plates.
V C Section 4850 Issuance of Plates Reflectorized Plates
VC 5200(a) requires you to mount both issued plates.
V C Section 5200 Display of License Plates
VC 11713.17(a)(2)(A) requires you to mount the front plate.
V C Section 11713.17 Front License Plate Bracket