[Taylor]

Are you mounting the KOP wheels lower than the treads? You'd end up with a vertical offset of 1.25" between the middle and outer wheels, since the KOP wheels are 6". You'd get a lot of rock with that design.
Also, consider that all the weight supported by a non-driven wheel is pretty much wasted. It's analogous to driving a rear-wheel-drive vehicle in the snow. Without sandbags in the back, it's hard to gain traction.