I think your set up would work. I dispose of mothers as soon as cuts root. Mothers are in gallon size nursery pots when they are trashed. Up pot cuttings a couple times before new cuts are taken. Always working with new green, nothing ever gets woody. I use a combination of T5's and screw in led's. This is small scale. Many mothers would require more space.
What measurements does this box actually have? Is it 60x40x40 inches?
my tent was /is 1x1x2 meters. remember the lights can´t be too close to the plants or they´ll burn which can be potentially dangerous. even autos can grow to be kinda tall-sih sometimes -they not all tiny. Plus the grow pot...
Not Inches its cm
My Flower Box are in cm size 80x80x160cm and I have 4 x55 Watt Cob LEDs
My Plan was not Grow big Mom's only have a small space to safe some Genetics in a small Form so Bonsai Mothers for later Growing if I like to why is that not possible in that 60x40x40 cm hight under a 50 Watt light?? I am very well known in LST so holding there Small mothers with some litte growth for take cuttings to transplant later in a Flower tent..
A typical COB puts most of it's light down in a 90 degree cone. To light an area 40 x 60 you would want that COB at least 40cm above the plants. You do have 40cm, but its eroded by the chip not being on the roof, and the canopy not being on the floor. In reality the COB will be 20cm from the top of your cuttings, and you can't put a 50w COB 20cm from a cutting. 10w is about the limit.
I guess you could put a mum one end and a 20 cell prop the other, with the light in the middle over neither. Some tissue over the cuts could lower the light levels further and a white/reflective board could help the mum. It's all rather crap though. Is there no other option?
It's the probox propagater S for good reason. Though you can keep a mum in a PC case if you really wanted to.
Think about the temperature too. Wont go with an ESL, unless you want switch to asparagus