Ruger 22/45 Lite
10/22 is nice and seems everyone recommends it.
Walther P22,small,lightweight,and interchangeable backstrap.
Agreed. The 22/45 is the best .22 pistol made IMO and the new Lite model seems to be exactly what the OP needs.
Ruger 22/45 Lite™ Rimfire Pistol Models