Steering was definitely an issue on this project. Skid steering was too unreliable and too unpredictable. It took me a few days to figure out the solution. The easiest way was to remove the steering wheel and attach a drill, simple enough!
This is intended only as a temporary solution since I can't exactly fit a child in the car the way it is. Either way, drive-ability went up exponentially. It became way more fun to drive. The modifications to the wiring couldn't have been more simple. I put the two rear motors in parallel on one set of relays and the drill on the other set of relays. From there I had to turn the switch on the controller 90 degrees and it was done.