WHY DO YOU NEED ALL THOSE SEATS. What, are you a rolling circus?
Get rid of the 60% side of your useless back seat so you have room for MOAR GEAR!
From the manufacturer:
Jeep JKU 60% Seat Delete Bracket
This bracket includes the necessary nuts and washers for installation.
With the 60% seat delete bracket you can now remove the 60% passengers side rear seat and retain the 40% seat. Bracket is powder coated black steel.
Installation requires basic hand tools and some mechanical ability.