monitoring active/backup routers

Hi all,

Let me explain the topology first, all of this is managed by a 3rd party WAN provider.
We have a lot of sites with 2 private MPLS connections, each with their own Cisco router and VRRP/HSRP running between those.
They have BGP running so our LAN IP range is re-announced from the backup router in case something goes wrong with the primary.

I would like to get an alert when the primary connection goes down, but my problem is when WAN connection 1 goes down we can still ping router 1's LAN IP through the secondary router.
I could monitor interface status or maybe even the BGP neighbor information, but this would require me to do a lot of manual work setting up correct monitoring for each site.
I already have each router's LAN IP and would like to just use that (unless there's no other way).

How would you tackle this scenario, ask the provider to put some ACL? Monitor an SNMP object and if so which one?