I'm not sure if sensor lights will mess with them too much. I've had outdoor crops for many years and the sensor lights didn't seem to have any effect.
I think maybe when outdoors the sun is soo powerful, and flowering is gradual, when some weak ass light bulb goes on the plants just ignore it...
If ya go that path just use low wattage bulbs (cfl) and direct them away from the plants and only turn it on when ya need to. The lumens from light bulbs dont travel further then a few feet.
I could be wrong but thats just my experience
Maybe ya could also use green light bulbs, if you dont think it'll attract attention. Plants wont recognize light in green spectrum