Seal Around License Plate Bracket

[SouthTXRVer]

My license plate bracket screws have stripped loose as you can see in the picture. I am going to go with slightly bigger screws to re-attach, but was curious what I should use around or under the bracket to seal it up. Butyl tape? Silicone? 3M 4200? There is about a quarter sized hole behind it where the wires for the light goes into the wall. Thanks.