I decided to do an experiment with my Mark Puette's Knight plate
I put metal plates in the back of my regular license plate to react with five powerful Neodymium Magnets, i even used a pair of homemade black "plastic tongues" to disimulate the rest of the plate because the European plates are little longer than USA's ones i put caps on the bots to disimulate the fact of not being screwed to the car and the result were wonderful!!
About if it holds tight i should say that it holds "enough" tight. I drove one time with it mounted about 30 Km having highway, poblation's circumnstances and when i got off the car thinking "DUDE WHERE IN THE HELL IT'S MY PLATE!! MY GIRLFRIEND REACH IT FOR ME, SHE'S GONNA KILL ME!! WHAT I'VE DONE!!" i look at my back and see it mounted, my face was complete cartoon like in that moment
The better item to show with your pics!! Better than photoshop!!