Why diesel? There were different low-quality fuels (alcool) for training duties that avoid overloading Junkers.
Diesel was not very much in use by Wehrmacht, and refining of Romanian crude was giving 2 liters of diesel per one liter of gasoline (and another 2 liters of oil suitable for street lights). Conversely, in Sept 1939, Wehrmacht used 5 times more of gasoline (vehicle-grade plus AvGas) than diesel, and great increase of aircraft, tank and truck numbers kept the ratio, if not icreased it. For comparison, German 'civil' usage of diesel and gasoline was about equal in Sept of 1939.
The synthetic fuel factories were also delivering diesel fuel as byproduct, roughly 1 litre per each 3 liters of AvGas (tpically 87 oct and higher) produced. In 1944, Germany was producing about same quantity of AvGas and diesel, plus a bit less of vehicle-grade gasoline.
My bottom line for all of this - since we're getting the diesel fuel anyway, let's use it.
Alcohol as fuel sounds great, but it will require devoting a good percentage of arable land to it - fuel of food dilema. One then needs factories to produce alcohol is quantities needed. Since we're making factory to make fuel, better make factory to make hi-oct fuel.
I've already suggested that Jumo 222 is cancelled, so Jumo will not be that overloaded.