dad off again,total red herrings again, we all know our number plates are illegal and we dont need you to tell us.
As the vast majority of trials, and you and your friends dont ride road trials whats the size or shape of the mudgaurd got to do with it. FFs back in the 70 80's we had stick on which werent legal then.
The manufacturers arent going to do anything cos its a british problem brexit or not.
You can get the add on plates which are a ssdt requirement anyway so your point is pointless. No prizes for that here.