Avoiding the "cage aggression" by feeding in a separate tub can result in not only stress, but "Oh look! My human taking me out of the tank. Must be to feed me!" = snake going into feeding mode every time you take him out of the tank.
Top-opening cages/tanks are usually to blame if there's any "cage aggression" since our hands swooping down is a lot like a bird or other predator would. I like to use the "Tapping method" to knock my snake out of feed/aggression/defensive mode. Usually when he's in his hide. I'll tap the ground, then his hide, then lift up the hide, put it back down, and repeat a few times just so my snake knows it's me and isn't surprised when I scoop him up to take him out.
