There is no need at all to make the snake to another enclosure to feed it. My snakes get fed in their enclosures because if I even tried to move them on feeding day I would be bitten. Feeding in the snake's home enslosure will not cause him to become aggressive. My snakes are normally big babies when it is not feeding day.
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A little bit of ingested substrate will not hurt the snake at all. What type of substrate are you using?