I've heard that for the ones that small, paper towels are best, as you can monitor the "output".

But it may make it difficult to keep the humidity right, plus, with 4 in there you wouldn't know who poops and who doesn't. So unless you can separate them, I don't know if paper towels will make a difference.

But, I have heard some little ones getting impactions from trying to pick insects off of substrate and getting a mouthful of substrate in their mouth.

You are right, shame on the breeders for sending such teeny ones out. I HAVE seen them for sale for as tiny as 3 grams, but that is for sale to a actual home, not a middle man. Even then, I would not sell them that tiny.

Thing is, it can take up to 4 weeks for them to start eating when they are stressed from a move. And they grow quite slow, usually. So you may be in for the long haul