30 + Teams? Not obtainable. Not that many big boats. Little guys (like us) don't have enough fuel capacity. It would make a cool one off event, but never work as a part of a series. And others have recently tried similiar "classic" offshore endurance races, only to moderate success.
The future for powerboat racing in the US is short course fan friendly events. Days of the Benihana running for 200 miles 15 miles offshore are over.

I would certainly like to hear Justabum's suggestions though....

I think most people like the idea of a long distance race, but the argument against that concept is spectators miss out on all the action. Most of us can agree on both sides of that. I personally think the answer to that would be to shorten the Key West track to 3 miles and run one class for 200 miles which would equal 67 laps. This would make it a long distance race that spectators could watch from shore.

And as for the rules, there would be none. The length of the race and water conditions would be the equalizer. I don't think it would take long for the big unlimited boys to figure out that their high horsepower 200mph boats weren't the answer for this type of race, and that eventually the preferred setup would be a 368 Skater or something along those lines with the new Mercury 860's. With all of the classes put together you would have a nice field running for most likely 2-3 hours. I would also be willing to guess that with the bigger, higher HP boats breaking down more often, there would be plenty of surprises with underdogs winning.

Another option to add to this format, and flame me if you want, would be to have a caution and pace boat come back out if there was an accident on the course. This would tighten the field back up for more competitive racing.

It's only 106 miles round-trip. Several smaller boats made the run in the 3 years it was held awhile back. And this was a run-what-you-brung race. Not limited to race boats. That is why you see pictures of the Mercedes MTI along side of OffshoreDrillin's 42 Cig and the 28' Skater of Jim Lee. Several others as well.

Good example was the Don Aronow race around Long Island. Pretty much long distance, rough water all the way, I don't think that many followed it. Where is it now? Didn't hear about it this year.