It is not necessary to use a feeder tank. Feeding in the snakes enclosure does not make them aggressive. However, you should avoid putting your hand in the enclosure for a while after feeding, as they may still be in feeding mode and may mistake your hand as prey. Always give them at least 24 hours to digest the prey before handling again. I personally go 36+ hours before handling. This prevents regurgitation if they become stressed and gives them plenty of time to come out of feeding mode.

I have six ball python and two Brazilian Rainbow Boas and I put none into a feeding tank. I have never been bitten by any of them. They are docile and healthy.