Have never understood the whole reasoning that leads people to think that the snake will start thinking your hand is food.
For one if you change water often, clean often and hold often, why would one, out of say 7 cage openings per week, opening for feeding make the snake believe every single time it will be fed from then on? That just doesn't make sense to me. If you are doing the proper cleaning and watering that is.
And another thing is that I believe instead of the snake "being aggresive" when fed in cage, I would think that the snake calms a bit because it is handled during each fed. Instead of being fed in cage, and maybe hardly ever handled. It is getting regular, although short handling periods just by feeding when you remove it and put it back home. One would tend to think that would affect its behaviour, instead of thinking it will associate that one cage opening out of 7 with food.
Just my thoughts. I fed in cage.