So, just to clarify, you're arguing that Donald Tusk has offered exactly what you want (except - in the absence of viable alternative solutions - to Northern Ireland in order to honour existing bilateral agreements implying no new customs borders there).

Do you think this offer is more or less likely to still exist if the UK insists that it doesn't need the EU's stinking trade, defaults on its financial obligations to the EU and enrages an Irish government with veto power over any hypothetical future deal by re-erecting customs borders with the north? (Even before considering the UK's ill-preparedness to attempt such a gambit means the direct short term consequences would hurt the country)