FWIW, I just had a similar problem. I needed a bedroom at a higher temperature than the rest of the house because of a disabled relative, but it had to be a consistent temperature.

They have extension cords with built in thermostats but I like something more programmable.

I bought a Philips wiz wifi-controllable plug socket (I already use their bulbs) and I took my ecobee room sensor and put it in the room. Then I used smartthings so it turns on/off the heater based on temperature.

Anyway, not sure on your application but there are lots of options for this.