Thruxton Thruxton R - Few Questions

2 rows of 64mm high characters with 13mm between them and 11mm top and bottom comes out at 163mm high. You can work out the allowed widths the same way. I'm pretty sure my maths was correct.

 

I think a lot depends on who stops you,I have heard people say that it must have a dealer name and address.
But the link I added should give you everything you need

 

Yes I already had that document. No extra writing is required apart from the BS mark.

I almost always have plates that are a little 'wrong' (although less so with latest rules) but they are obviously legible and not trying to be difficult to read and the police have never bothered me. As you say, it depends on who actually looks at it.