Last Monday's Telegrope (Business pages 1) headline somewhat like:

"Gove admits no smart borders until 2025"

The message I take is that applying for things like export licences or carnets fit this scenario.
I would have expected some on-line form for carnets, sometime, so maybe it will all be piecemeal and not properly joined-up. Like a lot of Government.
When I needed a carnet in the 80's it was large Chambers of Commerce like Birmingham that did the service.

If a pro-Brexshit and pro-Tory paper like that has to publish such headlines you can't dismiss it as rumour. They are pro-business after all.