You know about the free Bas-Rhin records available online, right? That's where I saw the baptism. Kehl, no idea. Strasbourg's collection has a whole lot of dioceses available, if your small town was considered part of it. Otherwise you might need to look at towns around it for records. One thing you could try is looking at a later Decennial Table from a town to see if your surname is there, which would imply that he might have come from that area. Tough job, though.