They don't have to QRZ you do that. A few years ago, one of my kids decided she'd cut school and go to the beach one day. Oh, taking everything with you is just too clunky, so nobody will find the keys in the center console. We'll be right back. Yeah, right. 20 minutes later, the car is gone. "Hmmm, I thought I parked it right... over... there." Some skell stole the car, took all of the information in the glove box, and my chip key to another vehicle that was on the key ring (along with the house keys). The car is sold for cash on an Internet classifieds website, along with a professionally-made title (can we say someone's running a racket?). The person who bought the vehicle was detained as they went to register what was reported as a stolen vehicle. We got the vehicle back, but all personal belongings were stolen.
Fast forward one year. With the chip key and the info from the glove compartment, these mutts come back and steal yet another car - right out of my driveway - almost exactly one year later. The vehicle was recovered after it was sold for cash on that same Internet site along with a professionally-made fraudulent title (racket, anyone?), except I guess the actor felt the heat and ran off once he had cash in hand, leaving the buyer with a stolen car, an empty pocket, a fraudulent title, and a key in his hand. That vehicle was also recovered minus personal belongings.
Moral of the story: nothing is safe, ham call plate or not. Secure everything. Use steering wheel locks. They can break them off, but it won't be a quick getaway, which is what they want. In and out. Use odd screws to put your plate on. I did, and it screwed the thieves up completely. Go to a local hardware store and ask for security hardware. Disassemble the plate area and put a backer with a nylon lock nut. The more time they have to spend depersonalizing your vehicle, the less valuable it becomes to a thief. I have both APRS and commercial tracking devices on them now. Leave no personal information in the car. Make copies of anything that's needed and carry a bag or briefcase that is pulled with the driver. If anything does happen, file a report right away. The faster it's listed as stolen in the database, the better the chance it will be recovered if it's not partsed-out or put on a boat to Central America.
This was a big live-and-learn for me and none of you need to relive my mistakes. Don't let it stop you from call letter plates, if that's what you like, but be careful all around.