Never had a problem, since I met MonkeyProof we've only been pulled over once, so the CHP officer could check the truck out. Technically twice, they check for violations when you go to the Santa Monica Peir, we had no front license plate.
A few years ago (okay, maybe 15 or 20), I noticed CHP ticketing parked cars along Azusa and San Gabriel for no front plates.
This was before the Forest Adventure Pass was needed to park.
I had one threatened to ticket me when I stopped on my Vulcan to take a leak at a rest stop near Dawson Saddle.