Simple: if it proves too difficult, don't do it.

I watched the trailer, and it doesn't mesh with anything I remember from the book. As the GP says, the book is disorienting. Not because of internal monologue, but because of the language. It places new words in essential places, where you can't really parse the sentence, and have to form some sort of impression. The rest of the imagery has been done to death. Some bits from the trailer looked a lot like Blade Runner. But the neologisms, feeling out of depth, that's an essential part of the book, never done in movies AFAIK, and I don't see it in the trailer.