Ceiling mount heater
I just hung the same Max Heater in a job where the size was 28x36. It not only heats the garage very well, but it also heats most of the addition upstairs when the door is left open. The sidewalls of the garage are 10’, and it and the addition upstairs are well insulated. It is mounted directly to the celling by unistrut, which provides the needed clearance, and exhausts out the sidewall. IMO, you don’t need to roast the workspace, and in my own garage, which is the same size, I work in about 60* temp.