License Plates Stolen Along With Bolts/Screws

In January, my front and rear license plates and the mounting screws or bolts were stolen from my 2013 200 Limited when parked in storage. Since the car was new to me last October, I have no idea what type of screw or bolt was used to mount the plates. I'm in Ontario, Canada which requires front and rear plates and we are metric here. I'm planning on taking it out of storage sometime soon.

At the rear, there appears to be two rubber/plastic mounts that take a short chunky screw. I was able to attach a short M6 bolt to this mount but I don't know if that was what it was designed for. Can anyone tell me the type and size of the proper fastener to use?

In the front, it looks like the plates were simply screwed to the plastic bumper with a short chunky screw (a very flaky setup). It looks like a similar size to the rear mount. Again, any idea what type and size to use?

I was thinking about ordering High Security Fasteners Metric M6 Anti-Theft License Plate Screws from Amazon. Which of these would work?

Amazon.ca : HIGH SECURITY FASTENERS