Not sure if the Outbacks have license plate issues like the Imprezas, but if they do I bought plate holders that use the factory screw locations along with 3m VHB tape to insure your tags don't go flying away. On the Imprezas the plates sit directly against the paint in the front and back and the plastic anchors are very easy to strip out. They strip so easily my dealer used special screws they bought from McMaster Carr. To date buying aftermarket plate holders is about the only permanent mod Ive done. Here's a link if you think youll have issues. Front Lic Bracket by C&C CarWorx to fit 2015-16-17 Subaru Outback Wagon OW-15-FP | eBay
Nice thing is they provide caps to cover the screws so it will take a meth head an extra couple seconds to steal the plate