Shimma is totally correct. If you are uncomfortable pulling over at a certain point you have every LEGAL right to put on your emergency blinkers and continue driving until you get to a safe location (i.e. gas station). It helps if you call 911 to tell the operator that there is a car with flashing lights behind you but you don't feel safe pulling over. They can usually confirm whether it is an actual police officer.
And in Washington, a front license plate is required. But we don't have to put the tags on the front any longer, just the back.
Sorry that he was a jerk. I understand how they can get that way. My husband has been accused of being rude (and I'm sure he deserved it!) and the only excuse I can offer is that they have a very difficult job and sometimes they get very jaded. Their sympathy can be very limited and it can be hard for them to relate to people. It's mostly because almost every person they deal with lies straight to their face and they just get sick of it.
It could also be that he's had a bad experience with someone who drove a similar car. Or even someone in your age range. It's hard to know why .... sometimes they are just jerks in real life and in their jobs.
But you should be able to go to court and contest the ticket - sometimes the judge will reduce it and sometimes throw it out completely. It seems a little excessive for such a minor offense. And it wouldn't hurt to write a
polite letter to the police station just mentioning the officer's behavior.
Do NOT be accusatory or rude, just state the facts and of course how you felt ("I felt"...not "he made me feel"). The letters that get the most attention are polite, to the point, and also admit to whatever they were doing...I'd mention that you were truly not aware that having a front license plate was required. Feel free to send in photos of your front license area to show that there is nowhere to attach a license. That would help in court as well.
Sorry you had to deal with a jerky cop. It's not your fault that he was rude. I will say also that when my husband got more than a couple of letters complaining about his interpersonal skills he took notice and he does a much better job interacting with people he pulls over now.