Nothing personal, and I'm sure this will make me unpopular, but it's a mouse (25g average) in with a 950g snake for 20 to 30 mins.
If you're worried about that mouse eviscerating your snake in that amount of time, something is wrong somewhere.
Leaving a mouse in with a nearly 1000g snake for 20 to 30 mins so it can eat in peace, is not even close to dangerous.