If you want her to eat with more consistency I would downsize, I would not suggest a 20 gallons for a snake until it is at least 500 grams let alone having a 200+ grams snakes in a T8 for most of them it does not work, I would also suggest the use of Aspen or Coco coir chips or mulch as a substrate.
A snake in the 200 grams should be voracious if it’s not you need to provide more security and you do that with a smaller enclosure and very tight hides.