I have a small plate on both my bikes for years and only had any grief once, I've been stopped before and they haven't even mentioned it.

The once I got grief was in Wales in July with another club member when we got pulled at 107mph, the cop told us to keep it under 90mph and gave me a £60 fine for the plate but didn't report me to the DVLA! Remarkably generous of a traffic cop I thought, but was SO gratefu!