tbh this from the IEA sounds an awful lot like Barnier's 'dedramatisation' (as explained by @tconnellyRTE last week ). An Irish Sea SPS border. 
Though I think it understates difference between animal & food checks. Does it mean opening a large proportion of Asda trailers for physical inspections?
Here's a massive assumption in the IEA report 'Continuation of VIES'. Currently only EU members are part of VIES. Even Norway doesn't have access.
Another sneaky line: 'Dispersed checks – ad hoc in border vicinity'
The WTO national security exemption makes an appearance. WTO experts will tell you this is actually much more plausible than the frontier exemption other people have being going on about. (Federico Fabbrini at DCU has written about it.)
But the wider point is that the EU is unlikely to allow a hole in the single market for two years, no matter what the WTO does or doesn't think.
