I got a smaller plate made up for the Testarossa (in Black too - yes I know very naughty) to fit nicely on to the front spoiler lip. Touch wood I have never been questioned about it despite having been pulled up for casual questioning by Old Bill on a couple of occasions. I would say that the plate is about 70% of the height of the standard plate, which I guess makes the letters approx 70% the size they should be. Could be worth a try - you can get them made up in white with black letters. Would give you an extra few cm of clearance and would 'almost' be legal.
When I lived in London I used to have a cracked front number plate (legal size) in the luggage compartment with sticky pads on the back for that age old story of 'a speed hump ripped it off half an hour ago officer, I'll get a new one made up and will stick it back on properly with some fresh pads over the next few days.' I think a copper would be having a seriously miserable day to give you a fine after that story. The most he should give you is a producer, whereby you have to get it sorted within 7 days and have an MOT test station stamp the form before producing at the police station.
You do of course need to stick the normal plate on using self adhesive pads for the annual MOT - I guess Matt will start experiencing that additional headache very soon
