I've caught a lot of shark and grilled a lot of shark. Not store bought packets of filets. I will tell you right now, if you do not catch that shark and immediately gut it, then let it swim for quite a while, your meat will taste like crap (actually cat urine). By gutting and letting it swim it will get the urea out of the meat through the skin. And yes, a fully gutted shark will swim behind the boat for a half hour on a line. That's why you can be shark bit at the dock when a shark was killed on the boat. It's all muscle memory. Remember, their brain is the size of a pea or a small walnut with very large sharks. They don't think, they eat.
The problem you will have is if you have chummed the water, other sharks will take a bite out of your catch and you wont end up with the length your speaking about. You wont have to worry about the last third of the shark because it will be eaten. That is why small shark is favorable for smoking/grilling.
Finally, the shark MUST be skinned prior to cooking or it will not be able to be eaten. In fact, no one will stand next to the smoker due to the foul smell.