> Why not consider a small 1000 watt Honda Inverter/Generator.
> It will run all night on a small amount of gas.

There may be other uses for electricity at the hangar, otherwise...

Why combust fuel to make heat to expand a gas to push a piston
to spin a generator to make electricity to heat some wires
to heat your oil?

A more efficient, lighter, cheaper, smaller package would use the
combustion to generate the heat to (heat some air to) heat the oil.
There are a number of propane and kerosene heaters available.
e.g. http://ultimategear.stores.yahoo.net/airpreh.html

-bob