Well if you can get ahold of one I'd go for a live rat fuzzy (aka rat crawler). They are perfectly safe to leave in with the snake overnight if you have to, since they have no erupted teeth to speak of. Most of my ball pythons seem to react very well to the movements of this size of prey. Enough movement to trigger a strike, no really fast movements that might put some snakes off or just make them give up if they are a bit of a lazy hunter.
Personally I'd let the snake feed in it's own enclosure. Ball pythons are ambush predators so hunting from a place they know and feel safe in has a tendency to make them more confident in their hunting skills (sorry to use people terms for what is actually a very natural snake process with no emotional issues attached to it).