I don't even know you personally caprice but been dealing with you long enough on here to know that you did not spend that much money on those things. I just can't see you doing it.
If you did for some reason get them, go to Wal-Mart and get the stick on Velcro with 3M backing. That's how Ed would probably do it and they would help him pull an extra 1200 pounds on his hitch.
Seriously though, the only good I could see those things working for is stopping frozen slush build up from forming right behind the front tire but that's what they would look like anyway, once mounted. I know you're not serious though. Show a link for the original ad when you bought them....
If you did, use 1/4" hex head 1" long self tapping screws. Keep them waxed up nice and shiny..