I've always fed on substrate. I've used eco earth, reptibark, cypress mulch from the hardware store, and currently (best imo) is reptile prime (both the normal and fine, though I prefer the normal).
I find very little sticks if you're heating with a blow dryer after they thaw (and I thaw in water) and the amount that does is so small as to be negligible; plus coco fiber tends to be known for being easily digestible, as far as I remember hesring.
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