Aerospace as a discipline has tried just about every propulsion system under the sun. What you're proposing has already been flight tested on an unmanned vehicle, albeit with many smaller props for a larger effective prop disk than the two you're proposing. This is actually better, because electric motors want to use rpm control, so you need to keep the moment of inertia of the propellers low. The efficiency penalty of smaller props is overcome by having many of them arranged closely together to create a large effective prop disk.

For a hybrid system to be worth it, you need to claw back more efficiency than you lose in going from mechanical energy to electrical energy, and then back again. For cars, this is generally the case, because they're always accelerating and decelerating. Their wide operating band means that the engine will always be a game of compromises, which is why sticking a motor and battery in the loop and decoupling the engine from the wheels is beneficial. But planes aren't like that; they go from setpoint to setpoint, and they stay in a given configuration for long periods of time. They have very narrow, highly optimized operating bands, so hybridization just isn't as effective.