I'm always the outcast on this topic, the pariah.
I have absolutely NO problem leaving a well-fed, well-watered rat in with one of my snakes for more than an hour or two. I don't do overnight but it has happened once or twice (on accident) with no ill effect.
A few points:
- I have multiple hundreds of snakes. I don't have time to sit and watch each of them for 20 minutes and then take the rat out if it doesn't eat.
- Some of my snakes NEVER eat within 20 minutes. They only eat after the rat has been in the cage for a much longer period of time.
- If I monitored every single feeding I wouldn't have time to make this post because I would be feeding 24/7 and would never do anything else.
In almost 20 years of doing this (hundreds of thousands of feedings) I have never seen a well-fed rat simply attack a snake. It just doesn't normally happen. If you throw a starving rat into a tub with a snake that doesn't want to eat, you may have a problem. If your rat can drink from the snakes water bowl I think you'll be fine. Unless you have an aggressive strain of rat they are pretty darn docile until they get very hungry or very thirsty.
Now, I know nobody who regularly posts here will agree with me on this but I'm cool with it. What I do works for me and I have not had an animal damaged yet from rodent bite (knock, knock).
If you have a ball python that doesn't seem to be eating in the 20 minute range, consider trying what I say. If it makes you uneasy, sit there the whole time and read a book. While you're at it, toss a piece of rat chow in the cage, too. That will give the rodent something to eat if it gets hungry.
Regards,