Feeding a snake outside the enclosure is just the worse idea, setting you up to get tagged, it's not a matter of if it's a matter of when. They are in feed mode hours before being fed and hours after being fed, therefore you are setting yourself up for a bite every time.
There is not one single advantage in feeding outside the enclosure only inconvenience and risks. Not only risky for you but risky for the snake should it break a tooth while biting you.
Your snakes will have not issue transitionning.
Most people do feed in the enclosure, those that do not were usually misinformed, and led to believe a persistent myth.
I have fed hundreds in their encore without issues and regardless of the substrate.