That would be about the maximum density Id go, they need space and if you let them get too dense they get cannibalistic and eat the smaller ones.
Better of with something like 90-100 litre tub (25/26gallons) with a screen lid for ventilation. I keep 1000 in one of these at any given time.
Ensure your eggcarton stacks are no higher than halfway and escapes will be minimal.
Be sure to tie stacks with something, so they stay together as one unit and you can turn them on their side (so hiding spaces are verticle) and the droppings will fall to the floor for the most part.
Lots of raw carrot, replaced as often as they consume it, will provide moisture, as will fresh fruit/ Fresh greens and veg should be avail at all times but they will grow fast, so if you maintain your colonies by sizes, aka pinheads alone, smalls, mediums and so on.
depending on your breeding strategy, your feeder colony will be medium or smaller, larger ones being used for breeding.
clean and dry and well ventilated enviroment is the key to healthy insects. Humidity is important too, but ambient humidity, no moisture (excepting food) in the tub.
cheers
