While your boat is on the trailer, measure the height from the bottom of the trailer to the ground, then make plywood boxes or blocks 3-4" higher than that measurement, do the same for front(two boxes also at the beginning of the trailers "v"), then lower your trailer jack enough to put the two boxes under the rear beams, then jack up high enough to put the front boxes under the trailer front beams and that is it, no more weight on the tires and springs/torsion.