Erik,
If you genuinely think you have found a site of real historic importance, you want to start looking at ways in which it can be examined and recovered properly, and legally. The first step is to work out whether the wreck has been "abandoned", in which case title probably (though not necessarily) belongs to the State in whose waters it is located, or not. Can you work out who the owner of the wreck is/was? Research the rules of the State where the wreck is located. How, and under what circumstances, did you get the Coast Guard to scan the site?
Sounds an exciting project. Don't do anything that would cause you to cross the line and lose your rights to this wreck by breaking the law. Work out what you have to do to make it a win/win situation for everybody concerned. There will be a way to do this, you just have to work out what it is, without giving up the benefits you deserve as the finder.
Mariner