How often do you see number plates displayed tow vehicles and trailers whereby the owner has interfered with the number to alter its original appearance or format?
Below is what the DVLA advise on this practice and the consequences
It is an offence to alter, rearrange or misrepresent the numbers and letters on a number plate to form names or words, or in a way that makes it difficult to read the registration number. For example, you should not use fixing bolts to change any of the letters or numbers. Anyone with a number plate that does not display the registration number correctly could be fined up to £1000. In some cases, the registration number may be permanently withdrawn.
If you have misrepresented a vehicle registration number that you have been given or bought the right to under the Sale of Registration Marks Regulations, and the vehicle registration number is permanently withdrawn, you would not get back any money that you have paid for the registration number, or any other costs you have to pay.
You cannot use a registration number to make your vehicle appear younger than it actually is.
Vehicle registration numbers must be correctly displayed on number plates as set out in the Road Vehicles (Display of Registration Marks) Regulations (as appropriate). These regulations govern how vehicle registration number plates are designed, manufactured and displayed
Oh yes and please do not ignore the obvious: The number displayed on your trailer MUST be the same registration number as that of the towing vehicle
Further information can be found at https://www.gov.uk/government/publications/vehicle-registration-numbers-and-number-plates