If you have to overcome the resistance that a gyroscope provides to turn flex or rotate I think it makes sense to have the resistance controlled and distributed evenly over more tires than less tires. I believe that placing the motor nearer to the intersect of flex that travels from front to rear corners is the place where the resistance the gyro produces will have the least impact on the flex but its just a guess.

Motogp was doing some testing where they rotated the brake rotors in the opposite direction of the wheel and the bikes transitioned much quicker. By the same logic 2 motors on an rc car rotating in opposite directions would remove the gyroscopic resistance. Or a mass of equal size to the motor rotor going in the opposite direction.