As far as the luxe sensor goes, a lot of people mount them indoors near a clear glass window, one on each side of the house, and create zones to control indoor lights that way. But that doesn’t work for everyone because if there’s a light that comes on near that sensor, it can throw things off.
There are several which are designed for use outdoors and shouldn’t have the same issues you’ve run into with the other photocells.
Regarding the existing circuit, I’m not quite sure I’m understanding the issue. Can’t you just put any inline micro on that circuit to turn the lights on and off?
If you also want to add a switch, you can add a battery operated switch anywhere in the house that you want that could activate the micro via SmartThings.