Pad Heaters? Any comments recommendations, etc.?

The local mechanic is suggesting we add a pad heater (glues
to the bottom of the oil reservoir on our A-65). He says if
we keep it plugged in all winter it will not only keep the
engine ready to start in cold weather, it will minimize temp
changes and inflow/outflow moist air exchange in the
cylinders, which will limit corrosion.

I'd appreciate comments or suggestions from those with
experience. The Aircraft Spruce website says no STC is
required for these. Why not?

Last, Are there any other inexpensive, safe solutions we
should consider that would hold the engine and/or oil at a
constant temp? I would think there might be some way to
cover the engine compartment with old blankets and set a 75
degree thermstatically controlled heater or light bulb in
there.

Thanks.