Figured it out. Needed to remove the fold-down carpeted panel behind the rear seats, which revealed two coffee-cup sized plastic inserts in the underlying sheet metal. Pulled up the inserts and could then see that the bump stops simply have a rubber tip that presses through an opening in the floor floor pan. I was able to push down on the tips with a screw driver and dislodge the the bump stops. Now I can easily install a bolt-on after market bump stop from Pro Comp or Energy Suspension.