Set up your tubs as described above, it does work.

Also I've found that waiting for 10-14 days after their first shed and then offering a live hopper mouse improves the odds of them eating on the first try. If that doesn't work the following week I get a live large-ish fuzzy or small hopper mouse, one big enough to move around a bit but not big enough to hurt the snake, and leave it in the tub overnight. It's usually gone in the morning.