I do not believe the trailer has to be the full width of the boat. The Keels are very strong. Longitudinal padded beds that curve to fit the keel shape along with guides running inboard of the chines would align the boat and carry the load. If possible, the wheels could be between the beds. Something like this would be much less than 2-meters wide without the boat.
Keel rollers at the aft end of the padded beds will allow launching with less trailer immersion. They only improves recovery a little bit.
You can borrow a trailer to get your boat in and out of the water. This may work if you keep the boat at a mooring. Starting with an available boat trailer for at least an 18-ft boat, lash two heavy beams across the trailer and pad the ends where the hull will rest. After the boat is on this kind of trailer, slide it around on the padding until you are happy with the location (it is not hard to slide). Then lash it diagonally fore and aft and diagonally athwartships to keep it from shifting.
To get a boat off a trailer is pretty easy. First lower the trailer tongue as far as possible. Next place a beam under the boat just ahead of the transom. It should be wider than the trailer.? Block up the ends of this beam. Raise the trailer tongue as far as possible. As you raise the tongue, the aft end of the boat will lift off the trailer. Insert a second beam a few feet aft of the bow and block it up. Lastly lower the tongue to medium height and push the trailer out from under the boat. Reverse this process to load the boat onto a trailer.
