I live in North Idaho, My shop is an uninsulated steel building, no heat and extension cord power.
I can't really heat it as the tin will sweat in the cold, and condensate inside the building. Right now, I''m just glad to have a concrete floor and a roof
I've been working on insulation, I will probably use a natural gas Reznor with wood backup, if I ever finish my shop. In the mean time
... I use an unconventional heat source:
Seriously though, I love a wood heated shop.
In the dead of winter, I'll keep the gas heat at 45 degrees, and use wood if I want it any warmer than that.