Disable interface on cluster state change or ping monitor

My ISP provides 1 DHCP IP address, however I would like to improve availability of the subnets behind my Vyos WAN gateway when I need to do maintenance or changes that interrupt connectivity.
I currently have two Vyos routers with functional cluster, conntrack, ECMP OSPF and VRRP on one DMZ interface.
The WAN interface on one of these is currently disabled and they both have the same mac address assigned. If I quickly enable the interface on one router and disable it on the other, internet traffic is not permanently interrupted.

How can I monitor the cluster service state to enable the WAN interface when the cluster state changes or when an internet address is not available on the other system?
In other words (or psudo code)

if cluster (this node)state=standby or ping = 0
  set int eth eth0 disable
  del int eth eth0 disable