I'm not sure how those things work either. My best advice would be to start checking government offices about passports and visas early, and right before you're ready to go find the nearest American embassy or consulate and tell them what you're trying to do.
I live in Utah, which is in the mountains about 1/3 of the country in from the west coast. It's out of the way from almost anywhere, so you're not likely to pass through just by chance.
http://www.subsim.com/2008_subsim_meet.htm
Focus in on the United States and you'll find my pin, so you can see where I am (and a few more, the ones planning to attend the meeting).
The merchant ship part sounds like fun. I'd do it myself, if I were 30 years younger.