I would just make sure to blur out a lot, save only a couple paragraphs or so so it really is fair use. I would actually keep the logo and header info, as that can be considered fair use to verify the document is genuine. Just like on TV, they only quote a couple sentences out of an entire blured document. You just need to get the really juicy bits. Unfortunately, that may be hard with these BOE letters because the WT writes so much stuff to hang themselves with. Also, put the text you are quoting below the scanned image or on the front page with the image as a thumbnail so people can read it in text without opening the graphic. The image would only be to confirm that the BOE letter is genuine.
I know this is a lot of work, but you might want to put a synopsis of the letter on the site along with the quoted parts. This way people get a feel for what the document is talking about without infringing on copyright. It actually could be set up quite nicely and the WT wouldn't be able to do anything about it.