Why could Sonnet 27 not be about a woman?
First of all, the general mood of the poem is one of ghastliness and horror. If he has a fixation on a woman, she's not a very attractive one.
As he is weary and tired, when his thought s turn to this person, a journey begins in his head and works his mind, as his weary limbs have been worked.
His thoughts of this person keep his drooping eyelids open wide looking on darkness which the blind do see. This is hardly gazing on someone or something pleasant and comforting. In fact, this person is like a jewel hung in ghastly night, which fascinates and horrifies him at the same time.
It seems to me that Shakespeare is describing a fixation that haunts and horrifies him but also gives him pleasure, like an addiction. If he's addicted to a woman, she must be a gorgon or something.
I don't know, but it seems more like a homosexual fetish than anything else, something to which he cannot keep his mind from going to but which horrifies him also. Drugs? Alcohol? I don't think so. I think it's some kind of fetish. And though he can't resist it, he also doesn't like it.
I thought it was! Maybe SB was showing how messed up mentally the director is.