So much to pick apart here and I really don't have that much time....................
First off assist feeding and force feeding are two totally different methods. Force fed means there would be a meal in that snakes belly. Second the OP tried to assist feed so please read the whole post before recommending advice.
Why in any ones right mind would you possibly get your ball python that is well known to imprint on a food source stuck on something you don't have readily available? In the wild they eat when the opportunity presents itself, they are not in the wild any more. If you have a constant dependable supply of chicks, gerbils, ASFs, or hamsters AND don't ever plan to sell the snake to someone else then by all means feed whatever you want.
Hopper mice will get just about any hatchling balls attention. As long as it keeps moving and they stay interested in it, it will trigger a strike.
If you want to get totally technical please use Python Regius, other than that welcome to "Ball Python . Net"