Personally, I'd KISSimpl-er and go wild . . . if it's already starting to turn just go with it. Add some campden, maybe half the normal dose (~25ppm) to knock out the lower quality wild boys and let the healthy ones go to town. If it's already starting to turn you're gonna have a hard time stopping a full on wild ferment anyways without pasteurizing the juice, so just rock it.
Or not . . . your plan is also great.