The two issues of customs tariffs and "customs" checks on legitimate trade between and across the UK and EU after Brexit are not exactly news. They were in the public domain well before the Referendum - courtesy, for example, of HoC and IoM briefing papers that were largely correct. To give Mr Elphicke his due, whilst his pronouncements are by no means perfect, I cannot recall the other GE candidates for our constituency mentioning the problems or proposing solutions. His 'Ready on Day One' paper is referred to in section 6 of the (largely correct) HoC briefing on Transport:
http://researchbriefings.files.parliament.uk/documents/CBP-7633/CBP-7633.pdf
Because it is difficult and potentially wasteful to plan/build a workable solution when you don't know what 'what' is (and even if you do, is there the time in which to do it), a logical possibility is to move 'Day One' to match the planning/building/whatever. This is not without its problems either, eg. customs matters ultimately end up in the ECJ (which I take it we want to see the back of), and, were a solution to be constructing the Stamford transport park, then I suspect that any Brexit "deal" would see its completion as a tail and not a dog.