First, please stick to ONE thread - having four on roughly the same subject will lead to repetition and perhaps important details being missed.
You will need to confirm the current requirement for a footbrake with someone who can quote gospel and verse from some DVLA regulation. It certainly was the case that just the spacers would do, and it was a definite advantage, as you could get the 'trike' MOT'd at an ordinary motorcycle dealer, which is not the case for an MP3 LT with a footbrake as these have to go to a dealer who has shelled out the extra two grand to be allowed to MOT trikes.
Here's a good page all about licensing, read learn and inwardly digest:
https://www.trike-design.co.uk/information/trike-law/