Bale wagon tip-over

Due to access restrictions I finished bailing my last feild two weeks ago. It's a small 8 acre patch that is extremely steep and extremely steep. When I was picking up my bales with my NH 1032, my pucker effect was in full force, and I ended up hand stacking a few rows. So my question is, how easily can a bale wagon tip over? They seem rather top heavy and the two wide models don't have a wide set of axles on them. Has anyone ever seen a homemade stability kit, or any ideas of one?

Bale wagon tip-over