Anonymity? How many plate-less Mercedes are there in CA?
If I'd had a silver SL55 I would have de-plated it, in the hope that Steve Jobs would have got blamed for everything I did.
How common are Silver SL's without a license plate in that area?
Common enough that I wouldn't give it a second glance. I regularly see plateless cars in SF, and Mercedes SLs are popular in the Bay Area - stylish without being flashy. Most of the Ferraris, Lamborghinis etc. are down in LA.