I see nothing but disadvantages for the OP with your recommendation over a simple line level thermostat. The only possible motivation for doing this is because you want to use a fancy thermostat. Not too likely in a garage where the OP is considering going simpler (light switch).
OP: I used line level thermostats for my baseboards in my shop. Different type of heater but similar wattage. They work great - far better than the thermostats integrated in the heater that don't read room temp accurately because they're too close to the heater.
"The only possible motivation for doing this is because you want to use a fancy thermostat. "
Exactly!
Why limit yourself to the dregs of line voltage thermostats? Fancy thermostat? Why can't you use a good old Honeywell T87 in the shop? It's not like people haven't done that for the last 50 years or anything, you can use a multitude of cheap thermostats (unlike line voltage). There's no need for on / off operation unless you WANT it that way. MANY people do this, like a wood stove, you get it going when you get out there, but others like picking up their phone and setting their shop temp whenever they want.
To each their own, I offer only options. If all you see are disadvantages then just widen your view, it's a matter of perspective.
CC
