If your going to charter for tuna go with someone who is going to troll for ANY size tuna. equipt with spinning gear also to catch footballs. you'll have more fun and get to take home fish. like Van said.
If your looking to charter strickly for a giant all your doing is gauranteing the boat a days pay. you will spend hours staring at balloons or kites all day livelineing bluefish.
and as was said any giant you catch belongs to the boat anyways.
don't forget if you choose general catagory you have to keep all the extra saftey gear required.