Cascade calls it a swinging frame. It has two advantages. One is that you can "side shift" the roll into position. The second may be more important though. The rolls generally shift when transporting in a rail car or truck and get wedged together. By using the swing frame you can move the roll from side to side to break it free.

mounting a paper roll clamp onto an existing sideshifter would be very unsafe and i would not suggest it. As was mentioned it would offset the vehicles CG too much and could cause a tip over when the mast is extended. Trust me i have seen one tip over when raised and its not a pretty sight.

like duodeluxe suggested the only option i know if is the clamps that offer the articulating arms. The side to side motion is not alot but it is enough in most cases to center the load if the driver gets it close to center on top of the roll he is aiming to set on to.

As with any of these type equipment it is a specialty type application and requires a trained operator skilled in that particular type of production area.

Long Reach - Allied Systems offers a "Rotational Lock Out Valve" for all their rotating attachments. It prevents rotation if the carriage is not in the centered position. Perhaps the other manufacturers offer something similar.

Cascade makes a paper roll clamp that has a swing frame feature which basically works like a side shifting paper roll clamp.

Plus, you'd have to downrate it to account for a few extra inches to the load's CG.

I guess anything's possible- just not sure it'd be that safe. Having a rotating object offset to the side just doesn't sound safe to me.