Next time you design a box, just paint it white, use some masking tape or painters tape to cover the cracks before painting. You can use inexpensive paint, I bought a gallon of flat ultra pure white for about $7 at Walmart. Depending on the brand, its roughly 75-85% reflective, much better than foil at about 50%, no hot spots, easy to "install", no worries about it falling off walls, rippling, etc.
As for your clones, what is your cloning process? I just started cloning for the first time recently, and have had decent success with rooting powder I got from Home Depot, but recently a friend had me try Clonex, to me, it seemed that the powder actually worked better and quicker.
I'll be watching your progress, I have an Aurora Indica that is about a week and change behind your ladies on the 12/12 schedule, just barely showing preflowers now.