Well shoebox should be fine, as long as hasn't gotten any holes in it.

Try to feed him tonight, as long as its been atleast 5 days since you last tried, and if that doesn't work then I would possibly bring him to a vet.

Also it's a good possibility that the jumpy mice are stressing him out, and he could associate mice with stress and that could also be a reason he's not eating. The rat pup was a good idea, let us know how it goes.

P.S. - Just to offer some insight I useto feed my anaconda hopper mice before she grew a bit and I upped to adult mice, but once she went to strike the hopper mouse, and it jumped out the way at the last second and she caught her tail, and ever since then she won't eat anything that jumps around and moves. It's possible something like that could of happen to your snake and you just didn't see it because your snake is a shy eater and mines not. If the rat pup works, then I would switch to F/T.