I would be concerned about any exposed skin in super low windchills, but
it sounds like you had plenty of body heat radiating from your face this morning.
(I didn't want to believe it was getting that cold already but weather underground
says Sioux City was 31 at 5am. It's usually only a matter of a day or two before
the Chicago area gets what Iowa's having now.) Have you ever worn ski goggles?
When it gets down in the 30's I start covering my whole face, I can't stand having
any of it exposed because my eyes water and my nose runs. I haven't had any problem
with wearing sunglasses under ski goggles.
Perhaps you're fogging issue would be reduced with a lighter hat that lets your head
radiate excess heat away, and/or venting torso heat somehow so your head is not
in a plume of steam coming from your body.
This may not specifically address your concerns, but in case you're interested, here's how I've dealt with these issues:
Across my lower face I wear an insulated and vented mask, it extends from the bridge of
my nose to my neck, has a little "nose vent" angled downward, has mouth holes,
and fastens with velcro in the back, which means I can fine-tune where and how tight it is
around my head, which is important for directing exhalations away from the goggles. They
have some kind of bendable insert at the nose-bridge area that keeps the mask pressed into the gap between cheekbones and nose. I adjust it for tightness
at the upper lip/cheek area, and looseness by my neck.
On my head I wear a helmet liner which seems kind of thin but does amazingly well
once I warm up after 5 minutes or so. This comes down over my ears underneath
the sides of the face mask. If it's down into the lower 20's I have an insulated version.
Both are wicking and breathable which is important because I sweat like a horse at
the least amount of exertion, and give off steam/watervapor like a pot of boiling water.
(I wear this same liner as a hat in summer to wick sweat off of my skull, that's how light it is.)
On my ears I strap on a pair of those 180 earmuff things that clamp around the
back of your head or a pair of on-ear headphones for music, which work just as well
and are actually more comfortable.
Over my eyes I wear a pair of untinted wide-view ski goggles, wide-view to retain
as much of my peripheral vision as possible. The foam gasket will barely overlap
the top edge of the mask and the bottom edge of the hat, but must remain otherwise
sealed for proper venting.
If I feel my chest or neck begin to get overwarm I unzip my jacket to let steam vent
directly instead of getting channeled up towards my face. There have been times
when I took off my gloves to adjust a zipper or mess with my mp3 player and my
fingers were almost totally numb by the time I got them back on, but my face
remained perfectly comfortable(and no issues with dry skin either.)
If it gets down into the single digits I can put the hood of my waterproof/breathable outer shell
up over everything, but I've noticed my head and torso really warm up quick this
way, so usually if my hood is up I'm opening up a layer or two over my chest to cool
off(even in single-digit temps.)
I've been able to affect my internal temperature a little bit by modulating my breathing- inhaling through nose brings coldest air in, inhaling through mouthholes
brings barely warmer air in, and inhaling air through the mouth from under the mask
(possible because it's looser lower down) brings the warmest air in. Exhaling through mouth under the mask retains the most heat by channeling breath downward to neck and chest, exhaling through mouth holes or nose holes gets
rid of the most heat.
It took me a lot of trial and error (and frozen faceparts) to arrive at this setup, but it works perfectly from the mid 30's all the way down to -28(the coldest i've ridden.)
Just about every piece of cold-weather gear I have was bought from Dick's sporting
goods, with the exception of my headphones(best buy) and boots(redwing.)
If you managed to read this whole damn thing I hope it helps you out.