[YorkshireT]

To do this, South Africa is the place as I don't think they have the baiting rules they have in USA. To fly from Orlando to San Fran is 6 hours ish, almost as far as from the UK to East Coast USA, and it is a long way to go across multiple time zones for only 4 days- you would literally have 2 days there if you were there for 4 days total.
Have you looked on the Atlantic Coast? Not sure about shark diving with great whites, but there are opportunities to go diving on some good reefs etc I am sure.