Could I transport hay on the arm of a backhoe?

[AllDodge]

My CAT 416 has had a bale spear attachment added to the front bucket. The hoe can pick up more then the average tractor FEL and the hoe on the rear gives it good balance.

That said, I bought it used some years ago from a construction/farmer and used it quite often. He removed the center hook from the top of the bucket, and added a plate with a hole and cut holes in the bottom to finish the spear. I have not used as such

 

[Xfaxman]

For reference a 4x5 round bale can weigh over 900 pounds:

 

[Gary Fowler]

I have a much smaller TLB (B26 Kubota) than your proposed buy but I see no reason you cant clamp a bale of hay with the dipper stick and hold it in place with the bucket. The Con would be that the bale would be really close to the ground and you may damage (break the tie strings) if not careful. IF you are moving them from the barn to the feedlot, then not a problem.
I have carried whole trees clamped this way with my B26, sometimes smaller ones clamped with the bucket / thumb and then swing them uphill when travelling on a slope for more stability.

If you would be using the backhoe a lot for this, then make a long bar that would bolt into the holes for the bucket teeth so you could spread out the clamp of the bucket across most of the bale length.