I just want to point out Ryan, I have never seen or use coconut fiber but I dough lizards understand this medium in anyway?
I use leaf litter to cover my dirt-sand mix, it helps retain moisture and keeps the lizards clean, this is how I use leaf litter. Lizards do not nest in leaf they nest in the substrate under them.

I use sphagnum moss in the same manner as leaf, to cover my dirt-sand mix.
Mix sand with top soil in about 70% sand to 30% soil, 5-6inches then cover with moss or leaf litter. Proper nesting for these lizards involves a media that can be compacted by the female, lose substrate cant be compacted.

Maybe I am not explaining things enough, or maybe you guys don’t ask enough questions?