You can setup VLANs from each AP back to the CCR1036 if you don't want to put a router at each tower. That will keep you from having one huge broadcast domain. If you run PPPoE on the CCR, you will be okay, as long as the back-hauls are managed via a separate VLAN than is used to transport your customer traffic. Watch your L2MTUs if you start adding VLAN tags to your links.
It is okay to bridge from router at the bottom of one tower to the router at the bottom of the next tower. So your QRTs and Sextants can be pure bridge devices. However, you do not
want all devices on your network to be in the same bridge/broadcast domain with all the other devices on your network.
This may be the time for you to investigate MPLS if you are doing PPPoE.
Tomas Kirnak gave a very good presentation on this at MUM US2013:
http://www.tiktube.com/video/KHhE3aEKdD ... sDlIoFqoq=