I haven’t tried this method with a sugar-free sweetener, though I wouldn’t recommend it. Sugar is important for more than just flavoring in ice cream. It’s also key to a smooth, scoopable ice cream texture (which is why commercial versions are packed with the stuff!). Fat and sugar are both important. In fact, the more you reduce those elements or increase water-based elements, the more ‘icy’ and less ‘creamy’ the peach ice cream will become.