Re: Inconvenient Bahama sailing
"I wish it were easy to just find out how long you can stay in each state with a foreign boat"
That IS easy. In the same phone call, or mail, where you ask ICE whether your green-carded alien wife and bring her foreign-flagged vessel into the US without a cruising permit, you can ask them about where it can go.
If she is bringing it in under a cruising permit, then the vessel falls entirely under federal jurisdiction and it can stay anyplace in the US for the duration of its stay. State laws concerning boat registration do not apply to foreign-flagged yachts under a federal permit.
On the other hand, you probably will be required to report in every time the boat moves, even if that is from one dock to the one adjacent to it.
ICE will respond to your entry questions, and the USCG is very good about answering anything else. (Probably much better at answering anything else.)
Since they're both administrative agencies plagued by incompetent bureaucrats (no offense to the SAR teams) who are never held responsible for what they say, you might prefer to contact them the old fashioned way, in writing, and keep their replies in with the vessels documents. That will generally get you considerable slack if their instructions were wrong.