[Yaristock]

Why not drill the required holes then spray with underbody coating(entire wheel well) the dip screw in the same stuff and then attach. It'll be a b!tch to remove but it'll hold like nobodies business. I agree with you about inserting small metal rods shaped like the skirt and then plastered there with fiberglass, the only problem it would possibly cause is if it detaches due to flex, maybe using some sort of harder plastic strips to secure to the back for support without the possible tire puncture issue.