Do you consider a 'breathbox' or whatever your helmet manufacturer calls it a 'major' physical deflection gizmo?
Honestly, I popped one of those in my helmet, and left it in for the cold weather season. I'll take it back out in the spring, probably about the same time I stop wearing a sweatshirt under my jacket. Once I adjusted the bendy nose bit, I haven't had to touch it, and I honestly forget it is even in there. I found this much less of a PIA that applying anti-fog coatings that worked like crap for a couple days and then not at all until reapplied. I've heard pinlocks work well, but some people are more bothered than others by the optical artifacts caused by having a double-lens.
Another option is just get a snowmobile helmet. You can get a double lens, double lens and breath box, or double lens and fighter-pilot style sealed breathing apparatus (this is what I consider 'major' deflectoin gizmo) OR you can get one with electric defrost.
Chris