As you well know all studies on this syndrome represent short retrospective series or case reports. In the absence of solid evidence we can only speculate what is the "best" therapy .
The principle of management here is ofcourse SOURCE CONTROL- i.e.- exclude the perforation from the mediastinum. This can be achieved in numerous ways. The literature mentions large spectrum of possibilities: on one side of the spectrum there is non-operative RX, on the other side-total esophageal exclusion. In between, various buttress-flaps, tubes, pipes, and even simple drainage of the perforation through the bed of the 10th rib(on te left).
Obviously, in selected cases non-operative Rx is successful, but the success is defined post-factum and cannot be predicted. I have seen a patient such treated suddenly dying 3 days after admission.
So how you treat theses cases depends on how sick they are- the sicker-the more aggressive surgery should be, how late are they diagnosed, and what is the condition of the tissues.
In late- diagnosed, critically ill patients, with severe mediastinitis I would go for total exclusion with end cervical esophagistomy, stapling of the GEJ, and pleural drainage. Lesser procedures, ofcourse, may be as effective but in the individual patient-who knows?
As a flap to close the perforation I would prefer the mobilized gastric fundus.
Some late diagnosed patients are non-salvageable whatever you do- your patient?
As a junior Intern in Jerusalem I diagnosed my first Boerhaave's syn- presenting with chest pain, Homman's (Spelling?) crunch, pleural effusion- high in amylase. On the morning after admission, on Grand Rounds I presenetd this case to the local Chairman of Medicine (the local "God") mentioing the possibility of Boerhaave's syn. The "god" smiled, diagnosed "some sort of "pericarditis" and ordered cardiac echo. When the patient deteriorated gastrografin demonstrated the obvious diagnosis. I have learned then : a. this syndorme is often missed. b. always carefully listen to what your juniors have to say.