Did you ever end up doing anything to add heat?
My 20x24 detached garage is freaking COLD. I just had a 100amp sub panel added to the garage before Christmas so I finally have power in there to do some real work.
This unit keeps popping up on my google searches:
[URL unfurl="true"]https://www.amazon.com/dp/B07QM2H5TR?_encoding=UTF8&th=1[/URL]
I don't know that I want to hardwire it though.. I mean I could... I'm just lazy