Kerry, I'm in the insulated and heated group. Plenty of insulation and infared tube heat. Usually around 50 and then kick it up a little when I'm working.
I find that the older I get the more warmth I need. Thin cotton coveralls, over jeans long sleeve shirt and another layer if needed and maybe a sweat shirt till things get warmed up. If it's below 0 the heat goes down and I find some where warm to hide. The deep south looks better all the time.
Jim