Additional rear cargo bed needed. Where to purchase?

Good morning. We just recently purchased a 2014 Sportsman Sport 315TH. It has the happijac system in the cargo area and currently has one platform/bed. We are looking to purchase an additional bed for the system as it has been set up to accommodate an additional bed. However, we cannot find anywhere to purchase the additional platform to install for the bed. The dealer said they would look into it but they claim they cannot find where to purchase either and KZ tells me to contact the dealer directly. At a loss... Any suggestions would be greatly appreciated.