If you're going to resell them, you'll need to control their sizes. I should have PMed you more information earlier. With those size tubs, I'd imagine only a couple hundred beetles in each one at most. Four inches of bedding will do you no good. You're better to have more tubs with beetles and then have "rearing" tubs which you'll combine the bedding from the beetle tubs every 10-15 days.

If you let them lay for longer than that, you'll never be able to control size for re-sale. It's important that when someone buys 10k large mealworms, they get large mealworms! You're on the right track though!

You'll also need something for the pupae. I use to use a folding Sterilite box, it worked good. Put a piece of egg create in it and shake the new beetles off every couple days. Let me know if you need anymore tips. IMO, your time will be better spent on the supers. They will make you more money. They are a little trickier though in large quantities.