All boats have keels. Not just sailboats. The keel is the strongest part of the bottom of the boat. 80% of the weight is held by the keel of the boat.
The keel is often a structural beam that runs in the middle of the boat from bow to stern. The purpose of the keel is to help give the boat greater stability and control while moving forward. Without the keel, a boat might slip or skim on the water which is often common in vessels with an entirely flat bottom. In most cases, the draft of your v-shaped hull relates to the keel which is the part that runs the deepest.
Then the rest is all a balancing act. The long pad(stern pads), bow pads(v-pads), and screw pads all balance the boat from side to side or front and back. Your straps hold it all together.
Never ever put the boat on steel or only carpet between the boat and steel. The carpet will wear out and the boat will be sitting on the steel. If the boat is sitting on the steel, then going down the road with the trailer tweaking and bouncing. The boat will be rubbing on that steel. You have to look at these boats being egg shells. You will have damage. So make sure there is wood between the boat and the steel. It is always a good ideal to put carpet on top of the wood.
Wood and Carpet is you best friend hauling a boats
Another thing you never do is when strapping. Have that strap close or on the boat with out lots of padding(carpet). Again going down the road with the wind, bouncing, and tweaking of the trailer. The straps will flutter and you will get marks that burn into the gel-coating.
Try to keep the boat as level as possible. If you have the boat leaning to one side or another. The weight of the boat will be shifted. Meaning more weight is on one side of the boat then the other. That can, an may damage the boats hull. As well as throw your weight off to the side and you will be wondering what is wrong with your truck or trailer.