no not used that but I used to fit my plate with 3m velcro like what headlight protectors are fitted with you can just take it off while riding I had it on my r1 first 15 years ago it worked(well never got caught )
thinking..I'd get done for speeding, not displaying my reg and perverting the course of justice turning a £60 fine into a huge fine and possible loss of licence...hmmmm maybe I should go for it..