Hey Bro,
I just mix my perlite real dry and use lots of it and I dont seem to get much condensation on the walls or ceiling. I think that if you use perlite, you can keep the mix dryer than vermic, because not nearly as much h2o gets "locked up" in the vermiculite. More moisture seems to envelope the egg because of the very loose breathable nature of the perlite. The eggs are actually surrounded by humid air but they don't get as wet because they are not really soaking in the substrate like they tend to do in wet vermiculite. Perlite also doesn't seem to draw moisture away from the eggs as vermic does when it starts to dry out because of its less absorbant nature. I'd use as much as you can stuff in the egg box and keep it a bit dryer and I don't think you will need to cover them with anything to disapate water droplets. I've been using it for about 6 years now and I'll never go back.
By the way, what's this $h!t, I'm your boy now?!? (LOL)
Later Buddy.
Will