do 400w for sure. cool tube will make it possible. separate fan to exhaust the room and all will be fine. try to squeeze an osculating fan in there as well.
I would maybe try the 24 hours of light. If you only wanted to move by a couple hours you could slowly move in whatever direction by missing or gaining an hour here or there. Switching opposite is probably anyone's guess. Might workout might not. I would go with the 24 hours of dark then go...
I've done both with sour diesel and the filter worked about 50 percent better in smell control going through the filter first. You will be able to smell the carbon but no skunk. The other way will help a lot but will not work 100%.