An electric heater running off a 110~115~120V volt circuit won't do squat. Been there are tried it. You can't get more than 1800W that way and UL has those Heaters at less than that.
I'm in agreement with the 60~65 Temp range. My Nason Ful-Poxy says not to use it shop temp is below 50.
I'm still working out in my detached one car garage. Other than the Ful-Poxy I've been shooting Dupont URO Primer-Filler. I have a 170,000 btu Kerosene Forced Air Heater than I run. Takes the temps from 40 to 75 in no time.
Problem is both the Heater needs air while running and I have to exhaust the space when spraying and it doesn't take long nowadays to bring the temp's back down. But the ventilation is good so I can turn the heater on if needed during flash time's and I turn it back on once the final coat is on.
Thoughts and comments expressed by me are mine based on my own experience and research and shared here freely. I am not a professional nor make any claim to be as such