It’s hard to say without more info, but most WISPs that size use OSPF to control routing across the ring/rings and BGP to their upstream Internet provider.
The guys at IP Architechs have a few write ups and presentations on their blog page at: https://stubarea51.net/. You will also find some relevant presentations by searching the MUM archives.
I would recommend using OSPF for transit subnets/loopbacks and iBGP (peering to an RR with loopbacks) for customer subnets. Add MPLS if you want to deliver L2VPN or L3VPN services.
Here is a topology overview:
Take a look at this presentation for more configuration detail.
I implemented OSP with loopbacks.
I implemented MPLS, in this point, on option MPLS/MPLS/MPLS Interface (MPLS MTU) what size mtu should I use.
I have peering between all R1, R2, R3, R4 and R5.
We has implemented L3VPN
When R1 fail, all clients out over R5, but how CPE they should have two default routes?