I use velcro both at the back and the front, plus two screws at the front, with both front plates drilled at exactly the same position.
For the velcro, I've used four strips about two inches long on each plate, again at exactly the same positions.
The velcro does get "tight" after a while so pulling a plate off should be done gently from one end.
I keep the "not in use" ones in the car so that I can change over whenever needed....