I searched the web on the instructions on how to replace the license plate light bulbs on the bottom lip of the trunk and there wasn’t much out there for NC Miata’s. The instructions for NB Miata’s are identical but it seems many people were breaking their clips on the plastic housing because it has become brittle with age.
So I figured I’d post my experience. Nothing was broken and no tools were required to take the plastic light out to access the bulb. The only thing I used was a piece of string to loosen the backing of the light because indeed it was starting to get brittle and stick to the metal of the trunk lid. I went around the perimeter of the light and then when nothing was sticking moved the whole thing to the left, slowly and pulled on the right side down in order to get it out.
The LED is considerably larger than the traditional bulb, but it fits.
When I went to test the lights nothing worked. So I had to remove them again and reverse the light bulb until… Voila! we have light.