Are you looking to do this and make a living, as your only income? If so I'd go with a more efficient boat if your fishing anywhere north of Palm Beach FL. Maybe a 45C or 46C, both will serve you well and burn 1/3 less fuel than a 55. Your competition will kill you on fuel costs. If you going to fish off South FL. where you can troll out and back the few miles you need to go, either the 52C or 55C would work. But if your running offshore, fuel will kill you. If it's just for fun who cares, get what ever you want.
When you see these multi million dollar 60 to 70ft boats for charter they're not doing it to pay for the boat or to make a living. They do it mostly to keep the name of the boat out there and to keep the crew busy. To offset the cost of keeping that professional crew fishing daily and sharp so when the tourny money is on the line, or the owner and his guests are on board they've got the drill down.
If I was to run a charter boat, and try to make a living there are a few boats I would consider, but at the top of my list would be a 1988 to 1991 Hatteras 45C Re-Powered with Cummins QSM11's. Even if you find a nice DD 6V92 boat they're still 20 to 23 Knot Cruise, 25 to 27 WOT.
My reasoning is this.
1. Largest Cockpit in the 40 to 50 ft Range
2. Can handle Crew and 6 Charter Guest in complete comfort.
3. Large enough to be safe a 100 miles off in the Canyons, Small enough for just about any Marina.
4. Solid, Safe, Comfotable ride in any Condition at 20 knots while able to run 30+knots if needed.
5. Nice efficient Cruise of 27 knots Burning 35 to 40 GPH. "with Cummins" 21 to 23 with Detroits
6. 2 Staterooms 2 Heads so you can keep one Locked and all to yourself.
7. Big Bridge for a 45 with room for everyone.
8. You can Purchase one Starting from $75K or a Really Nice Clean One for $150K to $175
If you were to Charter fish for a living I would personally go this route. Again that's without having a little more details about where and when you would do this.
Miami to Palm beach a 52 or 55 would be ok, "Great Boats just Big". North of that, Fuel will kill you and South of that, "The Keys" Some marina's, "Holiday Isle, Bud-N-Mary's" etc you have to be careful with the Tide. My 45 Draws 4'6" and at Low tide and we drag the sand coming into Holiday Ise in Islamorada. A 50ft+ Hatteras would have to wait it out. A 50 is 5'4" but the 52 and 55 are right at 5' even or so they say.
Other Boats I'd Consider: Hatteras 53C, and Hatteras HP 46C. Henriques 44. $Viking 47$, Maybe a Post 46, a pounder in a head sea and can be scary down sea but built well, efficient and stable while trolling. I'd stay away from older Custom Carolina Boats because you never know what your going to get.
Where do you plan to charter? That would be a big help.
Tony