People have made money from the Irish border ever since it existed, and no matter what the arrangements are, they always will.
Irish country folk who look like they haven't got tuppence, are usually the shrewdest, and among the wealthiest people I have ever met.
I don't see how the UK can have a land border with the EU, which will effectively be an open border, but time will tell I suppose.
Personally,I think someones bluff needs calling on "The peace process". They use it as a threat to get everything and anything they want.
People forget that in the mid 90,s the IRA effectively surrendered, due to the flow of $$$ drying up, and a process of a dignified cessation of hostilities was being negotiated with the Major govt.
Then Blair got into power and the whole thing went horribly wrong. So, as I said, I think its time to call their bluff.
After all the terrorism in the Western world over the last 20 years, they would find it very difficult to drum up much sympathy or support anywhere.
In the end, the border needs to be effective at stopping uncontrolled immigration and any kind of terrorism into the UK, and if people start using it as a method of sneaking in by the back door, it will need to be as hard a border as is required to stop that. Even if it means The Donald sending his brickies across the Atlantic for a bit of practice before they start the big job in Texas.