The 3rd interpretation of The Turn of the Screw

I’ve been reading the analyses in the Norton edition of The Turn of the Screw. Readers mostly fall into 2 camps: 
1) The ghosts exist, and the children are evil. 
2) The ghosts are figments of the sexually repressed governess’s imagination. 
The 2nd interpretation is often called the Freudian reading. 
Harold C. Goddard’s essay, for example, mentions the governess’s lack of experience, her “excessively nervous and emotional” tendencies, insomnia, overactive imagination, and the fact that she “falls instantly and passionately in love” with the employer, and her love is thwarted. 

“When a young person, especially a young woman, falls in love and circumstances forbid the normal growth  and confession of the passion, the emotion, damned up, overflows in a psychical experience, a daydream, or internal drama which the mind creates in lieu of the thwarted realization in the objective world. In romantic natures this takes the form of imagined deeds of extraordinary heroism or self-sacrifice done in behalf of the beloved object. The governess’s is precisely such a nature and the fact that she knows her love is futile intensifies the tendency. Her whole being tingles with the craving to perform some act of unexampled courage. To carry out her duties as governess is not enough. They are too humdrum. If only the house would take fire by night, and both children be in peril! Or if 1 of them would fall into the water! But no such crudely melodramatic opportunities occur. What does occur is something far more indefinite, far more provocative to the imaginative than to the active faculties: the boy, Miles, is dismissed from school for no assigned or assignable reason. Once more, the hint of something evil and extraordinary behind the scenes! It is just the touch of objectivity needed to set off the subconsciousness of the governess into an orgy of myth-making. Another woman of a more practical and common sense turn would have made inquiries, would have followed the thing up, would have been insistent. But it is precisely complication and not explanation that this woman wants—though of course she does not know it.” 

Edmund Wilson belongs to this camp, and points out the Freudian symbols in the novella: “the male apparition first appears on a tower and the female apparition on a lake”. 
I’m in the 2nd camp, but don’t really see it on Freudian terms. I don’t think her love for the employer (after meeting him once) is the cause of anything, other than her unreasonable refusal to contact him when things get complicated, and don’t know if sexual repression is the explanation for her behaviour. It is perhaps in her nature to imagine things, make up stories, and see herself as a saviour. 
I think the ghosts are not real, or at least the children don’t see them, strictly because evidence shows that she is dishonest and an unreliable narrator, whatever the cause. 
The copy I have includes an essay by Robert B. Heilman, “The Freudian Reading of The Turn of the Screw”, in which he argues why the psychoanalytical reading of the book is commonplace and simplistic. Mostly, he responds to the arguments of Edmund Wilson and Edna Kenton. 
It is a rather good essay, with compelling arguments, but he doesn’t refute any of my arguments about the governess’s unreliability as a narrator, nor her obvious lies. He also overstates the seriousness of some of the children’s actions, to fit his narrative. I think, for example, that it is not out of character for an 8-year-old (Flora) to run off alone to the lake and enjoy her freedom—it is oppressing to always be followed by an adult. There is nothing particularly strange and evil about Miles stealing the letter either—considering the fact that he doesn’t hear anything from the uncle, his letters to the uncle are never sent, he doesn’t know when he’s coming back to school or going to another school, the governess and housekeeper (Mrs Grose) both keep information from him, the governess once talks about saving him (which he doesn’t understand), then suddenly his sister Flora gets traumatised and sent away, it makes perfect sense that he steals the letter to see what the governess tells his uncle about him and his sister. 
These actions only appear as evil to a mind like the governess’s, whatever she has. 
The only arguments from Heilman that I can’t refute are the ones I’ve already mentioned: the governess’s accurate description of Peter Quint before knowing about him, and the framed narrative. 

“The prologue tells us explicitly: at the age of 30 or so she is still a spinster, still a governess, and therefore still heir, we may assume, to all psychic ills which Wilson imputes to her at the earlier stage. But at this age she seems, to a Cambridge undergraduate whom, 10 years her junior, we may expect to be thoroughly critical, a fine, gracious woman who can elicit liking and respect.” 

That is something I cannot explain, unless Douglas, the other narrator, is also unreliable. 
So now I’ve just discovered that there’s a 3rd interpretation, from Allen Tate: 

“The governess doesn’t invent these apparitions; they merely use her as a medium. Because, obviously, the monstrous proportions of the evil are so great that they are beyond the power of any individual imagination to invent. There is something much stronger than the governess operating through her. She has her own innocent later existence, as is proved, I think, by the prologue of the story, where we learn that after this terrible incident had passed, she went on to other posts and nothing like it occurred again. It was some peculiar conjunction of forces which permitted this evil to emerge through her here.” 

I don’t necessarily agree that “the monstrous proportions of the evil are so great that they are beyond the power of any individual imagination to invent”. After all, the governess gets some facts from Mrs Grose about the depravity of Peter Quint and Miss Jessel, and the letter about Miles’s expulsion, to help her own imagination run wild. 
But what do you think? Is it the governess who is possessed by the ghosts?