I run 2/3rds plate in normal position (no plinth)
and sticky pads are fine (just make sure area is clean and you warm the area/pads with a hairdryer first

)
Although if they are really strict round your area then you wont get away with a 2/3rds plate anyway!
other options
REGAL car runs a stick on the bonnet front plate : you say you didnt like this?
You could buy one of the 'plate flippers' , which you could allow it to slide under front splitter lip with the ign off.
That way at shows etc looks 'clean' but legal when driving (does look cack tho!)