Ditch the eyecup: Pros: no more fogging. Cons: visible green light in eye socket.
There's this device that TNVC sells, I forget who makes it (Wilcox I think) but it's under either accessories or PVS-14 parts or both. It's an amber filter. It has a thick rubber ring and an amber filter and no eyecup. The amber filter significantly reduces the visible light around your eye socket, while only changing the color of the image a little (yellowish). Doesn't fog up, and you can keep it close to your eye (generally how you want it). Kinda costly, but nice. It's all I use. I also use their replaceable sacrificial lenses along with a Butler Creek flip up I modded for use as a pinhole filter.
I found that even with demist shields in the army, I still got fog with or without the eyecup. Especially when running around and getting overheated on cool nights.
Also be careful cleaning lenses and such. The coating can come off easy if you don't clean 'em right. It can be a pain sometimes. No alcohol this, no water that.