Go for it, I do it in all my enclosures, including my Kinyongia which are the size of baby Panthers / Veileds. My guys love them - and they dont last long before they’re all eaten up. The absolute largest they have gotten in my enclosure is about an inch long, still very easy to manage for a young cham.
Carolina mantids are smaller than chinese mantids, if there is serious concern, but seriously - they are not going to get large enough to hurt your cham. They need a lot of food and time to reach that size, and your cham will surely eat it long before then.
They are an easy, tasty snack - and it gives my guys a little excitement when they hatch.
View attachment 278090View attachment 278091View attachment 278092View attachment 278093View attachment 278094