Light diffuser in egg tub or not?

I am waiting on the arrival of my first clutch. The Reptibator is set up with my egg tub inside waiting for the little pearly whites. I have used about a 50/50 mixture of perlite and vermiculite, and I wet it enough to make balls that stick together, but only a drip of water comes out when I squeeze them. According to the Reptibator hygrometer the humidity is 71%, but with my Petco hygrometer I am reading 90% inside the egg tub. I am wondering whether I should add more water to the substrate in the egg tub and use light diffusers to sit the eggs on? I live in the south, so it is already fairly humid around here, and I worry about mold since it seems to be an issue even in daily living (nothing to do with reptiles!). I happen to have light diffuser sitting around from another project. I haven't heard of any bad experiences with light diffusers, but at the same time not everyone uses one, and I am not sure why. What are the pros and cons of using a light diffuser, and if I use one, can I just add more water to my already mixed substrate?

Thanks for the help!

To me substrateless incubation is headache free for ME, no worry about getting the right mix, humidity is never too low and eggs never get wet.

I have been using this method for YEARS and never had any issues, I setup my egg boxes and forget about them for the next 55 days.

Ultimately like everything else it's about trying and see what works best for you and makes you feel more comfortable.