Still want to be careful with open flame type burners but with just that stuff you can use them and not mess up finishes.
Only problem with salamanders is they burn through alot of fuel to produce their heat but dont distribute it very well. fuel oil inst cheap so you’d want to get the most of it. I have heard of people making HVAC and diffusers that hook up to a salamander to better distribute the heat they produce and make them more effective for larger garages.
big thing is to keep the ehat localized. You’d be amazed what a layer of 5 mil poly plastic sheet up in the air can do to retain heat in a barn style garage. keep the heat down and you’ll stay warmer, longer, and cheaper too 