I like the idea of having more motors. Personally I would go for a modular approach where you have one box talking to the car (brakes, throttle, gear selector, steering angle, ABS/ESP system etc) and that box broadcasts torque demand for each wheel. Each inverter is set up to listen to broadcasts over the bus (canbus?) and generate power based on request. Failsafe turns of the motors if error conditions is present on the bus and/or if torque request and status signals are corrupt/missing.
This way it you can easily expand the setup on the car from single motor, to dual (either AWD or two motors on one axle) or quad motor AWD for the big spender. You could probably have dual back and single front motor too.
Got some toys for testing. Water cooled 80kW/280Nm motor capable of 10400RPM