OK Fellas, I got this done...
First I cut the hole with a 2 1/8" bimetal hole saw about 1 1/16" above the plastic of the license plate light.
Then I primered and rust-oleum painted the hole
Cut off the excess crap from the plug
Drilled the mounting holes and primered and rust-oleum painted those too. Then mounted the plug and sealed it all up with silicone
Done! Thanks guys for your help.