Agreed, getting an off road bike a street plate in CA does happen, but, rarely.
Often it includes some fraud with the VIN number. I've talked with the guys
that get plates for the older 2-strokes, NSR, TZR, RG and RS Aprilias. They
all run the risk of having the plate revoked if the DMV figures out the
mistake. Get the Feds really pissed off and you might get the bike
confiscated as an illegal importation. They have been doing it with cars for
years.
The bike in my avitar is a 1998 EC250 that I converted into a SuperMoto.
It has had a CA plate since 2000~2001. I have been pulled over 3 times
in the past 14 years or so. Each and every time the officer just wanted to
review my paperwork thinking a 2-stroke was not street legal. Never got
a ticket and ended up spending 10 min or so BS'ing with the cop about
the bike.
Cheers.