The worst thing you can do is not have it full. It is moisture in the air space that causes the problems, both corrosion and somewhere for the fuel to gain moisture from whether the fuel has any ethanol or not.

But the last thing you'd ever do with ethanol in the tank ( say E85 ), is leave it sitting for a long period half full or very low. Either full to the brim, or with normal petrol flushed through.

Although there is a whole load of hype around the E10, it's a minor change. The change to unleaded was far far bigger, and the world did not collapse

And has to be said...didn't really improve much from it either, just the same as this E10 is largely bullshit.