[Sephiroth]

Seems to me that if we go down that route, we should start straight away with a target of 10 years to leave a Customs Union.

I fully understand how complex this will be and that 10 years might be overshot. The system would have to be capable of adapting to new rules that might come out from time to time.

If the EU wants to be difficult, it could easily thwart this on the basis of who pays, who does it and being 'scared' of the complexities.

You could come at it from a reverse direction. Leave with No Deal; collect all the Customs use cases that ensue and design the initial system (for 10 years on!) accordingly.

All depends, of course, on EU cooperation and their behaviour to date suggests further difficulties.

So the choices are, it's Remain or Leave with no deal. As you know, I don't care whether or not we remain (I prefer to leave), but if we do remain, we must keep prodding them with our picador sticks.