The Irish border has approx Dover levels of traffic passing through it annually. The difference is the infrastructure is likely to be secure areas, it’s relatively easy to stop a vehicle that you want to stop as it has very limited options on where it can go. The Irish border has approx 300 crossing points and some of them will turn into a network of roads so vehicles can go in any direction within minutes. And it is 300 miles long.
The hubs generally have secure perimeters, warehouses, etc
Remember there will be 2 sides to the border so the EU Customs will be enforced on one side and whatever the HM Customs decide they want to do on the other side.
Typically goods going across a customs
Border are declared twice - in this case when leaving the U.K. and when entering the EU.
Goods arriving into the EU have to be declared at the point of entry that will not change.
It’s 100% YOUR problem.