[EricH]

The problem you'd get with a second wheel is the lock-to-lock turning is 3 full turns. Most of the time, you'd only need a little bit of steering, but when making a tight turn, you can easily run into trouble. If that were done, I'd locate it off the drive shaft (structural addition may be needed) and link it 1:1 or maybe 1:1.5, then put a spinning flat knob on the additional wheel, equipped with a bicycle toe clip and most probably a heel jam of some form, to allow the driver to fully turn the wheel. Some buses have a small knob sticking up from the wheel; this would serve a similar function.