things seem to be going fine, that's a neat space you've got there!
How strong are those cfls? You could keep the plants in the corner, move the reflector and make a temporary wall to make the room tighter and increase side reflection on the lower branches. A low ceiling on the box will also help concentrate the light some, besides keeping the heat in the box.
As it seems, cfls demand narrow spaces to offset their low light penetration, and the relatively low heat they put out allow for very close placement. You said you'de like to make this a cfl-only grow and go with hps in the next, try not to give up easily!
Oh, and about your question about 100% dark: I've given this some thought months ago and it seems it won't kill the plants to have some light during flowering nights, but this will make them revert to veg hormonally speaking for a bit. During the next light cycle, they'll understand it's fall again and so time to flower, but you'll have missed about a day of bud development. The thing with nature is it has no commitment with productivity, only with maintaining the species, we humans are the ones to care enough for a couple more grams of herb!
But i do recall a friend who had a huge plant in her garden, over 8ft tall, and it never flowered in about 18 months, probably because of street, car or house lights. She took it down before moving and never saw any buds.
