Don't omit or underestimate the weight of required control gear.
These are not ancillaries, they are just as important as the motor and batteries and they tend to be weighty.
Me? I'd be looking to a hybrid as a practical solution in the short term.
Either electric augmented by a smaller engine or vice versa.
In either case I'd pick a single (Caravan?) and not a twin.
Shorter cable runs and no need for duplication.
Motor rotor built into the prop drive shaft passing through stator.
Regen on descent - maybe obviate the need for flaps?
Lotsa possibilities.