Isn’t it nice Ford gives the options to run different fuel types and has the ability to retard the timing with knock sensors? It’s wild how responsive they are to tuning and octane, like all cars. My SHO is tuned for E40 and gets an average of 17.5 mpg. It also has a 93 tune that can run different fuel types and adjust the timing accordingly.
The easiest way to get around low octane with no access to E-85 would be methanol. Between E85 and Methanol everybody has a chance to increase the power of a stock eco boost engine easily.