IFFEN

Hello, We are developing a VR zone of 15 m x 15 m for 10 players. We just purchased the HTC VIVE Pro headsets. How many total base stations do we need in order for the gameplay to be fluid with 10 players? I read that two base stations for the HTC Pro can be used for a zone of 10 x 10 meters. If I have four base stations, could I create a tracking area of 20 m x 10 m? If yes, how many players? For the moment each player will have a headset and the two controllers. Thanks!