I'm on the rack side. Two comments
If your load is all Paper at 40 x 48 x 60 it weighs a LOT more that 1000# more like 4000#
If the load is unstable and leaning, it may start the rack leaning and then you will have real problems. All rack relies on being plumb and level but with Drive in there is NO room for error. Drive In has no inherent L-R stability.
What kind of business are you in? Newspaper inserts or magazines?
I can help more with the racks with pictures or specs etc