You may have a point on tank heater pads at 0F on down. Our Itasca 12 volt tank heaters supposedly suck up 6-8 amps continuous, each (we have two), if not cycling and hence ON continuously. In less severe, but below-freezing conditions, I believe their average current draw per hour should be a lot less.
For extreme cold drycamping, IMHO, one should have at least a 400 AH battery bank, anyway, so electric tank heating should not be an issue if you're packing generator capability along, too. Personally, I wouldn't camp in cold temperatures without also having double generators along for systems redundancy. We have the built-in Onan for full electric heat (including tank unthawing) and battery charging if the propane system should ever fail in the field and we also carry a small Honda along with extra fuel for topping up the batteries every day - so as to not have to resort to the Onan or idling of the V10. The little Honda can even run a couple of our 150W personal electric heaters plus top up the batteries for backup, In an extreme emergency, long term idling of the V10 can of course heat everything and charge everything as long as the up to 55 gallons of fuel lasts.
IMHO, equipment flexibility and redundancy are the name of the game for RV boondocking - at least when one finally reaches the age where they are no longer immortal!