Don't use a separate feeding tank. Just feed in their cage. The whole idea of feeding outside was mostly applied to large snakes with large feeding responses like retics, burms, large boas. But that has been pretty much debunked now as most people have learned that after feeding a large snake doesn't just turn off, it can remain in feed mode for hours so try moving a 14ft retic who just ate a 5 lb rabbit from its feeding tub back into its home while its still in feed mode. As long as you open the cage and do other stuff other than feed only, your snake shouldn't get conditioned into thinking open cage=food. Plus ball pythons don't really get big enough to pose a life or death situation like retics, burms or large boas can.
I feed my 5ft+ red tail boa in her cage and have done so for 2 years and she is a sweetie. I take her out a lot as she loves the be handled. The only time she gets excited is when she actually smells a rat, then its game on. Same with my little BP, she is mellow till she smells a rat, then out pokes her head.