Are you keeping them for fun or trying to breed them?
I used to breed both species.
I worked out a very easy setup for finding eggs.
I used paper towel substrate and potted pothos vines as plants. The pots were actually some sort of plastic tub that were 4" wide in diameter and 4" deep. I used potting soil in the bottom 2/3 of the "pots" to benefit the plant and the top 1/3 was then filled in with peat moss. It was easy to find the eggs because they always laid in the pots, dumping some of the peat moss onto the paper towels in the process. So whenever they laid I knew it immediately because there would be some peat moss on the floor of the cage.
If the substate was peat in the whole cage, it would be hard to find eggs. They are pretty good at hiding them sometimes even in a 4" pot- without the visual clue of moss on towels, I would have missed many eggs. Sometimes even with the clue I was unsure because I still had to search around in the pot for them. There is always some risk of impaction also I suppose, though I've used it many times for humid loving lizards and never had a problem with impactions..
If I wanted to create a large "show" tank for cresteds or gargoyles, I wouldn't hesitate to use peat moss as a substrate. I consider it very safe- I even put a thin layer over the potting soil in my chameleon plants to keep them from picking up bits of dirt and gravel or vermiculite or whatever else...