It's not about a stepped hull. It's about placement and coring/construction of the hull. Your best bet is to have it in front of the foremost step. You want it at the very center of the "V", just off to one side or the other. It is going to have to be bonded to the hull with epoxy. If you have a cored hull, you are less likely to have good results. If you have a solid hull, you ought to have great results.