Silvaire1
I agree, I don't believe infrequent use of starting fluid is that harmful and prudent use as you mentioned is on target.
Just keep in mind it can contain as much as 60% dimethyl ether and most 4 strokes can't handle extreme pressures on ignition, especially cold. It also has no lubricating properties. Great used on high compression engines such as diesels however.
If you can wrap the cowl and preheat engine compartment while you get a coffee and do a preflight.....the engine should start with carb heat on by using the warmed air inside cowling to atomize the avgas.
Also I believe multigrade oils work well, however even if one drains the oil after flight and brings it into the camp in order to keep it warm, it does nothing for the differences in the engine metallurgy properties the next morning at startup.
As a fellow Canuk mentioned only a most dire situation on the ground would cause me to deal with a possible most dire problem in the air.