Why not put heat in your garage?
I put in a Modine Hotdog Propane heater Ceiling mounted
Bought it off the internet $400.00 for 70,000 BTU
Mounted it myself did the gas lines and Exhaust pipe
Let the Gas company hook it up
They make smaller models
The 70,000 heats up a 24' x 32' 9' ceiling in no time flat
I keep it set at 50-55 When I work in the Garage I turn in up a bit.