My brother in law has a much smaller NH 2310 (40HP) and it handles 4x5 round bales easily. He has moved a super sack (1500 lbs) of cow feed with it using his bushhog for counterweight. The rear tires were almost floating but it had no trouble with the FEL lifting it. I was surprised. With better counter weight, it would have been super easy. This was using chains on the FEL bucket. If he had removed the bucket and used the QA hay spear to lift it, that would have put the whole thing much closer and less residual weight on the FEL to start with.
You should have no problem using the 55 HP tractor with a bale on the rear and one on the front. Don't use those FEL bucket attached hay spears. They are hard on the bucket AND limit the weight you can lift by hundreds of pounds since it is so far forward plus have to lift the FEL bucket also. Get a QA hay spear and you will be SOOO happy.