Ran mine like it for 2 months as I liked the look but I always carried the plate in the cabin. To cut a long story short I got pulled in London on Regents Street which drew quite a crowd. (kinda good, kinda not as I got quite a lecture
I didn't realise it carried a fine so i said someone had just backed into me and having the plate in the car really helped, hence no fine. Now ive opted for a bike plate (again illegal) but at least it's displayed and I think it looks OK.