Bob...

I work in medicine and I got an old patient air blanket warmer for free - a
model that had been discontinued by the manufacturer. It's about 800 watts
and has a blower and heater and 3 inch plastic hose and is set at about 40
degrees C or 102 degrees F. Its a very sturdy metal floor unit with wheels.
My R182 is hangered (unheated).

I modified the heater by putting an intake plastic hose rather than having
it take air from the room. I stick the output hose in the oil dipstick
access and the input hose in the left cowl flap and I leave it on all winter
and I cover the cowl with a quilt.

The coldest mornings here are about - 25 degrees F but with this rig, the
engine is always a balmy 70-75 degrees and it heats the whole compartment -
engine, battery - everything.

I have pulled the plane out in - 25 degree weather and fired it up with a
couple shots on the primer like it was the fourth of july.

It soulds like the heater you are considering is similar to this.

Regards,

DB