couple things that might work,   turn off the spreader and drop the residue in a windrow, bale the windrow, you'll remove right around a ton/acre, run the stripper plates tight so a lot of residue goes through the machine.   
   second scenario, run a chopping head, run it lower, you'll trim the tops off of the covercrop   wait a  few days, rake it high, you will be around 1.5-2.5 tons/acre removal.