Staying in the customs union would also resolve the Irish border issue, subject to agreement with the people who are really setting the agenda, the DUP. Doubtful until the point of brinksmanship is reached, which won't be long coming now.

Interesting take on brexit and that referendum from the Guardian's editorial on 5 December:

In 2016, more than 17 million British people voted to leave the European Union. But, as the journalist Tim Shipman's new book, Fall Out, which covers the political turmoil of the 15 months since the referendum, makes clear, only two British people decided that this meant leaving the European single market, the customs union and the jurisdiction of the European court of justice.

Those two people were Theresa May and her former aide Nick Timothy. These fateful national decisions were their personal interpretations of the vote to leave the EU -- and theirs alone. As Mr Shipman explains, these foundational decisions of the UK's withdrawal strategy were not discussed by Mrs May's cabinet, let alone by parliament. Instead they were simply prime ministerial edicts to the 2016 Conservative conference. Later, they were included in the Tory manifesto for the June 2017 election, in which the party lost its overall majority, Mrs May's leadership was humiliated and Mr Timothy lost his job.

So two now-discredited people decided that the referendum meant that we can't be in the single market and customs union. You can bet your life that, had you asked the electorate what that actually meant before the vote, you'd have got an overwhelmingly clueless response. Theresa May, acting without personal mandate, has certainly "taken back control" of massive decisions that neither the people of this country, parliament nor even her own cabinet were party to. Yet we get all this guff about how undemocratic the EU is. I could say "what a joke," except that this is the most unfunny thing I can think of.