I used to live in Spring Hill... And I used to keep my sailboat in the St. Pete City Marina...
You will find far and few live-aboard marinas in the Tampa area today.
However, if you cross State road 19 going to the Gulf, along that road you will find several hiden marinas with good Gulf access. But as I said they are fairly hidden, but they are there.
Jim Lowry formaly Barlington Rd., Spring Hill