Boris cannot do that!
Also he does still have more than just himself to please. The EU would have to agree to this imaginary solution. The British and Irish people would have to agree to it.
Backstop = border on Irish Sea for indefinite period, so not allowed under the GFA.
Borders at ports in rest of U.K. for the entire island of Ireland = border on Irish Sea plus literally a change of U.K. status for part of Ireland, so not allowed under GFA.
That goes completely against the Good Friday Agreement (GFA) and whilst I have always viewed that very Agreement as being a failure in many respects and appeasement to terrorists, I would say to all those people who do use it as an excuse to scaremonger against Brexit, including Sinn Fein and the Irish Taoiseach, that you cannot pick and chose the GFA for your own interests and excuses and then not adhere to some parts set in place.
Good luck trying to walk over British people. Time and time again it has been tried.