if is behind the plate it wouldnt be track legal unless you always run with the plate down ,
if you have a fuel cell you could make a plate to cover the old tank neck opening for a push button shutoff switch to mount behind the plate..like this switch
http://www.summitracing.com/parts/fla-fr1013/overview/
i run a flaming river remote shutoff that has a rod to flip the switch off by pushing in ,
http://www.summitracing.com/parts/fla-fr1003-2/overview/ . i run the rod on the side the license plate with the supplied "push off " decal on the reverse lamp lens