I've used miracle gro perilite with light diffusor as well and haven't had problems. So have other breeders I know in the area (it's easier to find).

I found a place that has "regular" perilite in bulk and have switched to that (it's cheaper). But in a pinch I think you can use the miracle gro without issue. I've never actually heard of anyone having a problem with it in substrateless incubation.

Best of luck!!!