I have the plastic drilling templates, since I installed the cargo cover after buying it. The template is black plastic, and looks like a bracket itself.

You should drill a small hole first and then the proper size to prevent a crack.

I didn't do that and so I have a slightly larger hole. It doesn't affect the ability to hold the cover, but looks a little bad when I remove it.

Where are you? I'm in Michigan. Maybe I could digital photo them and make sure they are to scale, or maybe send you the templates to borrow. Maybe at some point I will get a new side trim piece to replace the one I damaged.