isn't creating a little hidden vent between the lens and the rims a good way to go? I have my Stormtrooper lenses mounted so that at the bottom there's a few mm gap between the lens and where the helmet should meet just as some added ventilation and that has seemed to work well for preventing fogging inside the helmet for an extended amount of time without having to wipe.
Im using shampoo for my lenses.. Everything works fine plus it smells good!! Pour some shampoo on them swipe it without water
I tried the gaps method.. But with fabric it doesnt work.. Sorry guys for my bad english