Failover betwen WAN and OPT without CARP, is this possible.

[tempura]

Is it possible to have OPT1 as just a backup for the WAN link? Without CARP. Its like, OPT1 becomes the default route whenever the WAN port losses its connection.

But, without using or deploying a CARP array.

[hoba]

Yes, create a loadbalancer pool and set it to "failover". First add WAN to it, then OPT1. Don't forget to modify your firewallrules at LAN to use this pool as gateway.