"The problem remains that’s is only one interpretation of ‘leave’, with no mention of what to do about the Irish border."
The Irish border is a non-issue as I have argued countless times on here.
"All leavers do not agree with those four proposals."
Then they should not have voted to leave. It was made more than clear by "Project Fear v1.0" that leaving would mean these four things.
"In fact, they weren’t even given the option on the referendum form. That means all leavers have had to make up where they stand subsequently."
As above, the question was "Leave" or "Remain".
The consequences of leaving were made very clear (principally by the Remainers). There were similarly no options for the those voting to Remain. It is absolutely certain that the EU will not remain as it is now and many of their policies for the future will profoundly unsettle even the most ardent of EuroManiacs. I don't recall any warnings being given by the Remain campaign of those dangers (the campaign being more concerned with reasons why we should not leave rather than why we should stay). There were no choices such as "Do you want to Remain provided the EU stays at it is" or "Do you want to Remain provided the five current candidate nations (who together would struggle to buy a pot to urinate in) are not admitted"
If people voted to leave - or indeed to remain - without being aware of the consequences that's their fault.