Super truck - should we hope this isn't road legal?

I say yes as long as they are use appropriately, maybe with an extra test required and other regulations like restricted road usage.

I drafted something very very similar to this up the Holloway Road late one night. It was unladen and was the most exhilarating ride I have ever had off the track

I expect you were drafting once of these, the double arctics are not about yet.