Yes, there are already baby naming ceremonies. I'm not sure what the name for the "godparents" is, but there's a different name. I think they're are about moral guidance, instead.
Why do you want any ceremony at all ? From my experience the activities
of most godparents cease at the church door. I had my daughters Christianed because I thought it was 'the norm ' , a bit like registering the birth. However my grand children were not Christened , in fact it was never even considered .
Im my experience, Godparents have nothing whatsoever to do with religion, just as hardly any Christenings do either. Both are just a meanless ceremony, on a par with all those weddings have I gone to in the last 60 years, where the couple have never set foot in a church again. Hokum.