Yeah if anything I would give the snake flagyl injections to stimulate appetite.

If you can get a hold of a live ASF I would give that a try. I wouldn't try a gerbil, they are expensive and sometimes hard to find. And if your snake imprints on them you are stuck feeding them. If anything, a ball python will choose an ASF over a gerbil since ASFs are their natural food source and gerbils are not.