Impound vehicle and all contents here on the left coast then pay fees + penalties to DMV, Pay the tow truck fees, pay the impound yard fees, $30 to $50 each day they have it, then pay the court system for the ticket you going to get, that is just for the vehicle with the wrong tag. If they find out and they will know that the tag or plate was stolen then a whole new set of penalties kick in including possible time in the grey bar hotel.
It has gotten so bad in Calif. that if you run a red light or do a Calif. stop (don't touch a foot down at the sign) it will cost you a min of $490 with all the penalties they add on. Hell, illegally park and it is $270 for the tow and $90 for the ticket with the $30 to $50 each day they have it.