I would suggest using the winbox gui. This should be easily implementable on the RB9XX series. What I believe You would need to do is remove all settings from your router, AKA reset to factory defaults and reboot. From there you will remove configuration (pop-up window on first logon) when you log back in (log in via layer 2/MAC address winbox login, because your .88 IP will be removed). Once you are here, create a bridge using eth1 - eth4 and also wlan1 in the bridge. For eth5, enable PoE (do not force, try automatic first) and you should have power to your PTP radio. Next, go to DHCP Server -> Click the red add button, and select the bridge you created previously as your interface. You should be good to go.
Do you need help setting up your PTP bridge as well? From your set-up it seems like a CPE/receiving side of the PTP bridge.