According to Grady the center of gravity for a fully loaded 307 with power is about 10 foot plus a few inches. If that is the case, it seems that your bunks are too short. You want to have the COG close to the the middle of the bunks. Simple math would say that the bunks should be 18 to 20 feet long. That assumes that the bunks fit flat to the hull and that may not be the case. I am not an expert on lifts but I assume that the bunk arrangement would be similar to a properly fitted trailer where for longer hulls , a second set of bunks ( target bunks) are used to support the forward part of the hull
