Reg plates

Hi there
Just got my reg number for my 4" agi.
I'm going to make a scale set of reg plates for it for the rally field, however for taking it on the road I'm not sure what are the legal requirements for the reg plates are. Could I get away with motorcycle style plate (square ones only on the back) or do I have to have ones for both the front and back?
I would like it to also be easily removed, what has other done regarding their engines?
Kind regards
Luke Crowther

I've used neodymium magnets on a bracket. Easy to remove and place. Also saves drilling holes to mount.

I use a motorcycle sized one on the rear of the towing trailer and a scale brass one on the front, no issues so far.

A good supply of neodymium magnets are in old hard drives, I now always break down my old drives for the super strong magnets they contain

Got my magnets from Big Teddy on Amazon, they are magnetic hooks. Unscrew the hooks from the magnets and then use the threads on the magnets to mount them to the brackets.