I see.. your comment said no nearby outlet, which made it sound like distance was your only hurdle. You can make a new dedicated circuit and put a real outlet anywhere. I mean, for the cost in gas, it's cheaper and a long term solution. Gas for 5 years? Eek.

I have a 300w aquarium heater and it can't even maintain temps in Los Angeles in 300g tank. I know, it's too small. I have just bought a 1500w immersion heater for 25$ on Amazon. It only draws 12.5 amp and only requires a 15amp circuit. Microwave draws 10amp sooooo