Ok I think I am going to proceed with installing a ceramic heat emitter. A space heater just doesn't make sense to me from an energy efficiency perspective. Why use a hundreds or even thousand watt space heater when you can have a 60 watt heat emitter?
This is my tub.
Would this heat lamp setup be sufficient for a tub of that size?
Heat emitter
Thermostat
Fixture or this one (not sure if that one will extend beyond the bulb)
I think I'd want as a low a wattage heat emitter as possible, because my plastic bin will be better insulated than a glass terrarium and require less energy input. I also want as little a chance of melting plastic as possible.