deluxestogie: You're right about volume-surface, now the way to improve insulation is to add some more layers of good thick styrofoam inside.Try to find the one with foil like leverhead sugested, has the advantage of extra protection against fire.Or some blanket like yours in cozy can.
Knucklehead: I do turn it off at night, but want a solution that makes me feel safe. For example, a smoke alarm wouldn't help if i'm to work for hours.
DGBAMA:I saw the ceramic heater and the modifications, you've done a very good job. I'll try to do something similar.