Information?....
As Karl has said, the towing capacity of the vehicle is rated by the manuafacturer and is usually posted on the vehicle idetification inside the door jamb.
There are 5 types of towing classes and each is designed for certain purposes and will only mount on certain vehicles.
For instance, your not going to find a VW beetle towing a class III or class IV trailer hitch. It's just not possible.
As Karl has said, the installation for classes above III will normally come with a transmissionn cooler. With the extra load on the drive train, the hydraulic oil tends to get hotter; and will cause the bands to slip. Automatic transmissions already have a cooling system that uses the radiator to cool the oil. The additional cooler is normally mounted on the front side of the radiator and gets the second pass of the oil leaving the heat exchanger of the radiator.
Here is a link you might find useful.....
http://hitches4less.com/trailer-hitch-classes.html
The only thing I didn't see was the use of power assist from the watercraft's engine, while loading up a ramp. It's used on a regular basis here at the deep sea ramps for the big open ocean fishing boats. They have these huge trucks, but still use the power off the outboards to get the trucks rolling up the ramps. As soon as the motor breaks the surface of the water, they kill the engines......
Back in the early 90's, I had a 19 foot Marquis with huge deep-V and used the in/outboard to help get the truck rolling. If I used just the truck, I could get it out, but I would, at some point, break traction. With power assist, I never put a strain on my truck motor or drive train.
Front wheel drive verses rear wheel verse all wheel.......well, that's kinda easy. All wheel would be ideal........but, when you look at the front wheel verses the rear wheel. The theory of pushing verses pulling comes into affect. It's easier to build torque pushing, than it is to pull. The front wheel drive will do better then a rear wheel drive on a snow covered road, but not on an incline with the weight of a 18 -21 foot boat sitting behind it, pulling upward on the front end. Center of gravity is lost.
This was a good thread. I enjoyed reading it.........and of course, putting MY two cents worth in also.........:cheers: