I had/have a similar problem. My girls were being disturbed by a orange street lamp which was basically shining on them all night long, even though the light wasn't intense. They wouldn't flower and finally I started covering them with a black garbage bag, making like a tarp over them and low and behold they started to flower. But, since I have done this, due to my work schedule, I haven't been able to cover them regularly at the same time every night for 12 hours. But, they are flowering like mad and now I'm in the 2nd week of flowering and they are continuing to grow (buds and plant). Some nights, I can't even cover them because of my work shifts. So, this leads me to think two things:
1. the street light didn't have any effect whatsoever and they just started flowering when the temps and season began to change or
2. They're giving me some false hope that everything's gonna be alright and then...BOOM, problems like hermies...
In any case, the black box seems like a good idea. I just don't know how big I would have to build it as the plants are growing in stature as the buds swell. I wish the best to you and will keep us posted!