I found a nice example of a Hatteras Yacht Fish Ext. Cockpit at the Ft. Meyer's City Marina, along the Caloosahatchee River in Florida. This looks like the 53' version, but might be larger. Some of the additions to this yacht make it interesting and a lot more usable. First, is the hardtop over the flybridge, with enclosures. Second, is the extended dinghy support brackets, providing a larger aft deck entertainment area. Nice old Hatt!
I have seen that boat in Key west. That is a 53' Yachtfish. The 58' yachtfish is the exact same boat as the 53' MY with the addition of the cockpit. The easy way to tell the difference is that the 58' Yachtfish has 3 windows aft of the side wing doors. two square windows followed by the sort of triangle shaped one.