As i see it the only solution to the 'backstop' has to be decided by Northern Ireland; not Europe or Great Britain. If it wants no hard border between the Republic of Ireland and Ulster it will have to settle for a hard border along the Irish Sea. This might encompass allowing all value added product from NI in free of tariffs but not allow transshipment of goods (and of course migrants) from the EU in through the backdoor. It's not a perfect solution but it might be the only feasible one.
There is a lot of pie in the sky fantasy about a sovereign UK in a global free trade zone. These are contradictions in terms. A national, integrated, industrial and agricultural economy will need a resort to tariffs in its economic arsenal. It was that way 200 years ago and will be the same 200 years from now. This 'inevitable' momentum towards an tariff free world is a chimera.
None of promises of an equitable, prosperous, peaceful global free market community have been met. Just the opposite the world is being driven into economic chaos. The West's economies have been deindustrialized, deagricultualized, and its vital industry has been undermined by a corrosive monetarism and financialization of the economy. Its leading to polarization of wealth and encroaching impoverishment.
As far as Bexit goes, the British are letting the tale wag the dog. If Northern Ireland is so attached to its Irish connections perhaps its time to reunite. Religion it seems is no more a priority in the North or the South as the Republic continues to distance itself from Catholicism and Ulster from the Church of England.
In any event the EU is collapsing. The riots in Paris have shown the malignancy at the core of the union has now metastasized into the heart of Germany and France. The UK has no choice. It has to see the reestablishment of its sovereignty as a necessity not an option in the changing European landscape.