Alberg/Pearson designed a plug to fill the well when the outboard was removed. I find that it's worth half a knot to have it in when racing particularly in winds 10+. There used be a a thread about a member that made a form from which to duplicate the plug. I don't think you have a weight or balance problem. Heeled over the waterline is above the edge of the opening for the OB. It messes up the water flow and creates drag as well as filling the laz with 5-10 gallons of water. The plug makes an amazing difference. If your OB is hanging off the transom the situation is much worse. I use an old Johnson 5HP that weighs 45 lbs. We pull it, put in the plug and lay it in the laz for day-sailing. Racing, we put it in the cabin to get as much weight low as we can.