I'm in the same boat. One plant will finish a week earlier than the other. It's the first and last time I will grow more than one strain, cuz what I'm about to do is going to be very annoying!
I believe that you don't need total darkness, but you shouldn't have direct light. I'm going to do a whole-plant dry, looking for about 10 days if it can work out. I'm planning of hanging the plant in the bathroom above the tub. That way I can keep the door closed and monitor humidity at 55%.
It will mean showering at the gym.
But if that looks like it won't work out, then I'm going to use your method, since no one seems to be squeaking that it will result in too much degradation of THC.