Wow. Kind of sounds like the nut is seized on the axle shaft. It's possible the shaft has been installed bassackwards, so that the nut is on the opposite side. Try reversing which pinch bolt you leave tight. Next up I'd ask what kind of impact driver you're using -- Harbor Freight units don't produce anywhere near the torque they advertise. At some point you need a really long breaker bar (or two), one friend to hold the opposite end, and another friend to hold the motorcycle. The axle and nut are 12mm hex recesses, but the use of 12mm hex bits instead of hex keys is strongly advised.