Prepaid and postpaid wifi CPEs with central user manager.

Hello, we are looking for the best way to set up a new wireless network that has certain requirements and any configuration advice would be appreciated.
There will be several RB433AH powered AP high sites installed and connected to these will be a mixture of MT and UBNT CPE clients.
Some clients will be permanent users (the majority) and the others pay-as-you-go or prepaid.
The APs will wirelessly backhaul over a short distance to the central where the main ISP connection is.
Here we would like to run an RB1000 router acting as a central user manager and hotspot server so as to manage connections, authentication etc. from a single location.
It is assumed that the best way to do this is for each AP to have one type of connection/authentication configuration for the permanent client CPEs (PPPoE?) and a virtual AP for the prepaid users where they will be directed the central hotspot server.
What is the best way to configure the APs and CPEs so that all traffic is passed through the RB1000 for authentication and management?