Take off that helmet and get a proper winter hat that covers ears well, or a high tech ($$) thin one for under helmet that has a fleece-lined band for ear warmth. Chapstick on exposed facial skin helps. For feet either (1) the toe warmers between shoe and wind resistant cover, or (2) winter riding boots. I often put riding shorts on over the tights for extra warmth.

For me the fingers are always a problem with gloves, but an oversized ski mitt with warmers works for warmth but feels so clumsy.

About 35F without much wind is my lower limit, I'm not a fan of conditions that could result in ice. MTB for any snow rides. Seldom that cold in Seattle region. Missouri winters kept me off the bike a lot.

I don't have a foggy problem in the cold but a runny nose problem. Sudafed 30 min before ride helps.