That slope trick is a lifesaver. I've also had good luck using a long metal pipe as a rolling axle through the center. Lets you steer it like a giant wheel.
Seriously? A metal pipe through the center? That sounds like a great way to launch a bale straight into your fence. I tried something like that once and the whole thing just buckled and spun out. Seems like a lot of work when you could just nudge it with the loader and be done in two minutes.