Personally, I would have a couple of questions/concerns. First, is it selling so cheap? Second, he's willing to drive from Florida to Michigan towing a relatively heavy boat with gas prices being as high as they are right now? Keep in mind the old saying.."if it sounds too good to be true.....".
Also, what stood out to me the most when reading your post is "Florida". Find out if this boat is used or ever has been in salt water (as I'm sure you know, just being in all that salt air has its prolems).
Here's something to consider....call a dealer somewhere in the vacinity of this gentleman and see if you can arrange for this boat to be thoroughly gone over. This still isn't bullet proof for several obvious reasons but it might work. When we're talking about this kind of money, I personally would go to any lengths possible to make sure I'm not getting a lemon.
Good luck and let us know what you decide.
Just my 2 pennies worth.