The problem with ethanol is it absorbs water, which at greater altitudes (lower temperature and pressure) freezes and blocks fuel lines. For that reason aviation fuels have limits on ethanol content.
Could we redesign the fuel system to (safely) remove the water somehow? Or prevent the fuel from absorbing moisture in the first place?
It would have to be hermetically sealed from creation to combustion at 37,000 feet. I’m sure it’s theoretically possible but so difficult as to be untenable.
Maybe you could chill it to precipitate the ice just before loading it on the plane?