does your inlaw know about the grow? would she care? i would imagine that she is likely going to open the closet in her room... for just the two days, i would think you'll be ok. i asked a similar question recently and near as i can tell it would be like a cloudy day. just don't change the timing...

with regards to being an entire week, idk it seems a little risky to me, you might want to just leave all the lights on and have the door open so air can move freely.

Assuming you have everything wired correctly, the cfls are not going to get hot enough to light anything on fire esp just plastic. before you leave i would give the girls a good healthy watering, and plenty of light. you'll just have to fight your mind about your place catching fire, nothing caught fire when you were veggin, and now the lights are on for less time. i think you should be good.