No worries. Here is what it all means:
V5 is the testing specification established by the Trailer Hitch Manufacturers Association. Nothing to do with the Class rating, just the testing on how it's built. Just about everything now days will be stamped with the V5, hitches, balls, receivers, etc.
So basically the hitch can support 7500 lbs with a max of 400 lbs of dead weight on the tongue. If you use a WD hitch then you can go to 912 lbs of tongue weight. The reason for this is the % of trailer weight vs. tongue weight. Campers are normally somewhere between 10-15% and boats are normally somewhere between 5-10%. Some people prefer heavier and others like the lighter side. This will prevent too much weight being applied to the rear axle and lifting the front wheels up making steering not as effective. I can't remember where my bow rider was on the tongue weight, I know it was around 8%'ish I think. It hauled good and never had any problems. Remember that value will vary all over the place depending on what you put where. If you load down the bow of the boat, the tongue weight will go up quickly, and if you load weight behind the trailer axles the weight would be reduced.
Also most boat trailers use surge brakes and normally don't use WD hitches, as they can interfere with the surge actuator.
As for the GCWR you might be able to find it in your manual somewhere in the towing or specifications section. Whatever that number is take the GVWR away from it and that is the max you can tow. You can determine where you are in relation to the GVWR by going to a scale at a truck stop, and simply weight your truck. My guess is based on the number of 1163lbs payload in your sticker your car should weigh about 4800 lbs.
My truck has a rating of 5000 lbs and 500 lbs of tongue weight with no weight distib hitch and 12,500 and 1250 with a WD hitch on the factory installed hitch. With my new hitch its 18,000 lbs and 2000 lbs of tongue weight and with WD its 18,000 lbs and 2500 lbs tongue weight. So as you can see the numbers are greatly different between the factory and aftermarket. However the number I have to take into account is the GCWR, because if I had an 18K trailer, I would need to remove the bed and cab to get the weight down!
Its all a math thing on the numbers and what you can and can't haul. When you approach your max limits of the truck you will really know the load is back there. I hauled my bow rider originally with Toyota Sequoia, which was overweight by quite a bit. I really knew the thing was back there, and was nervous about doing long trips, however didn't have any issues. When I got my truck I really didn't know the boat was back there, it was night and day difference from a towing perspective. Running from the house to the boat ramp, I wouldn't think twice about using the Sequoia, however on the long runs cross country it was very exhausting as I had to fight the thing the whole time on the highway. Two lane roads were the worst especially when a semi passed going the other way. That was the reason to get rid of it and get the truck.
While I don't want to have you do anything illegal, you should weight both the truck and boat and find out the weights, as you can't plead you didn't know. You will have to make the decision as to do you haul it with the current truck or not. Like I mentioned the most critical will be the GCWR. I looked it up and here is the info from page 4-55 of your manual in the picture. So it will be close, at 11500 GCWR. You have to subtract your vehicle weight from this number and that will give you the real number you can use. If it was me, and it was short trips, I wouldn't worry, but on longer trips I might be concerned.
Look more in the section on hauling trailers starting on 4-54 and it gives you some info.
Here is a very good worksheet on weights and how to measure things if you're interested. I highly recommend it. If you go down and weigh to get your numbers, make sure you go in and talk with the people, as you don't want a busy scale, as well as you want to work out a price before you do all the measurements. If its really hopping at the truck stop they don't want to get tied down with someone doing multiple weighs. Go during a slow time and talk to the manager. If your out in the sticks a good place to go as well are grain elevators. Most of them are on all the time and you can read them at night, just talk with the people to ask to use it. It can be free there unlike the truck stop that will charge you.http://www.your-rv-lifestyle.com/suppor ... ghform.pdf