Cargo light install question.

[Sklptrljay]

I want to install a cargo light and I am pretty good on the installation itself. My question is about how I can reduce/eliminate any damage to the paint. I wish I would have cut the hole before I painted, but I didn't know I would want the cargo light until I saw the truck all done. It just looked kind of bare to me.

So what is the best way to cut into the sheet metal and save the paint around the cut? Any tips are appreciated. Thanks.