A common mod for Japanese import MX5's is to convert one of the reversing lights to be a fog light. It seems to be a logical conversion, looks ok and doesn't have any real trouble at MOT. But I'm assuming this sort of conversion isn't IVA friendly? The absence of the e mark and it's location within the light cluster both suggest instant fail?

It's the distance from the brake light that's a problem, I believe.

There is a guidance note in the IVA manual about converting lights to add Fog for imports.