Push-pull configuration aircrafts usually feature identical engines and propellers working only in tandem for multiple reasons like higher speed, better climb rate, reliability, cost, ease of maintenance, etc.
It may sound unpractical for piston engines were saving fuel will not outweigh the downside of one engine being a dead weight but may be a good idea for lighter electric or a combo, where engines may also be optimized for different propellers.
Can it be possibly beneficial to have tractor prop for take-off:
- blown lift
- no FOD risk
- less noise outside
and pusher specifically optimized for cruising:
- larger diameter as no ground clearance issue
- no parasite drag
- more stability
- less noise in cabin
Benefits to consider:
- higher achievable speed
- higher altitude
- still two motors for redundancy
Stowing nose prop.
Foldable prop should be cheaper than VP.
Less take-off power.
Electric motor for tractor could drive 4-bladed prop at peak power.