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.