The question is....
Is there really anything out there that really will prevent the outside of a scope from fogging when you step out from the AC into a crappy hot and muggy day near sunset to plunk a deserving coyote?
Bausch and Lomb makes a good spray called fog shield. It works very good. I use it on my glasses at work. I'm in and out of walk in freezers and coolers all day long. The only issue I've had is when I'm in a freezer for a long time and it's very humid out water droplets will form on my lenses. But no fog so I can still see. I think you can get it in pre moistened wipes and a spray.