Cuttysark
You do not know me but I know the boat. First everyone knows this boat as a wing keel and you are correct the weight of the boat should rest on the keel; however, the first 10 of these boats had a swing keel version, some with winglets. I think only the first 10 boats were that way. There is a diagram of the swing keel version in the boat information. Go to that and pick hunter, then click on 23, the click on down loads and go to the bottom for the diagram for the download on that keel. As for the wing keel fixed version, the hull was beefed up; ;however, there are some things going on.
Here is my take on this. First I do not know if this is a Hunter supplied trailer. See if it is a Kens Welding or KWS. If not that is the first mistake of the previous owner. Second, is the keel tray rotten or not, third does the keel tray fixed with a metal base and finally are the bunk boards rotten.
However, the very first picture and description gives away what is wrong. The bunks should be designed to support the length of the hull. Second, the supports should be straight up and not at an angle. Then there should be no additional two layers of wood attached to the bunk boards. Then there are other things that make me wonder if this trailer was for storing a boat only.
First you need to correct this now, not in the spring. You will need to buy longer supports and readjust to have them standing up and when you cut them have about 4 inches extending under for future adjustment. You may have to add side supports to the uprights so they will not allow the upright supports from leaning over. Rip those additional boards off. Check the original bunk board and if need replacing, replace it. Then check the keel tray boards to see if rotten and if so, replace. Then raise the bunk board to fit the contour of the hull. You may have to raise them a little higher to get the weight of the boat somewhat off the keel tray to allow the fiberglass to resettle. Then in the spring, recheck the hull as the biggest thing at this point is to allow the hull hopefully to reshape itself. Then we can talk again but get that water out of there and if means using a heater for a short while as long as you are there to get any ice out, do it. Do not leave any heater on unattended.
Also I am not sure if the boat was strapped down during transport to allow this. You may also have some indentations of the hull where the bunk boards are as well so when fixing, make sure the bunk boards rest on the hull evenly both sides.
I was a former dealer who was the top dealer selling this boat. Not bragging but just letting you know I still remember some things about this boat. I am retired.