Ive read removing the snake into a different container to feed it so it doesnt associate your hand/lid with feeding, reducing the risk of getting bit.
If you argued that reaching your arm into the snake's cage once a week would condition them to expect food each and every time you reached your arm in the cage to do other things, you could make an equally convincing arguement that feeding in a seperate enclosure and removing them from the cage each time to do so would condition them to expect food each and every time they are removed from the enclosure.

In other words, the whole "feeding inside the enclosure increases aggression" arguement is a load of crap.

Your snake will need about a week to get accilmated to its current setup. Make sure you have lots of cover on the ground, lots of places to hide on both the warm and cool side, and consistent, optimal temperatures. A couple of weeks in those conditions should turn a scared, stressed bp into a warm, hungry mouse murderer.