"I of course cannot and do not recommend anything deceptive but 'creative' thinking might help. <VBG> Jim"
You know, Jim, I was pretty much OK with your admonition to keep replies factual on the staff board. But when the staff posts comments like the one above, it really undermines your credibility to make that request.
Whether or not it's what you meant, that statement appears to be a "wink-wink," advocating some sort of flim-flam to create a document if none can be obtained. Hardly a principled position--even implicitly--for the staff to take.
And while anybody's obviously free to ASK any question they care to, for my money these fine-point legalistic issues aren't best answered on a bulletin board anyway. In this case I'd be calling, e-mailing and/or Googling the cruise line, the State Department, and perhaps the Consular Section of the Mexican Embassy.