Find out the weight of the ones you plan on moving. My 3 pt capacity is only 900lbs and I can move them no problem. (The ones I get weigh about 600lbs). It's also not too unstable on the rear. Keep it low and drive slow. If hitting slopes, drive with hand on the 3pt lever and IF you feel yourself getting tippy, just drop the 3 pt.
I've since gotten rid of the 3 pt bale spear in exchange for one that goes on my loader. I'm about at capacity doing it that way but getting the big square bales (750lbs), I can stack them two high with the loader but not with the 3 pt.