WAN failover with single outbound policy?

We have a failover setup between two WANs. Right now there are two outbound IPv4 policies, one for each WAN connection. Is it possible to make a single outbound policy that contains both WAN connections as the Outgoing Interface? 

I've done it with some other rules that use App Control to push specific traffic to one of the two interfaces, but want to make sure it would work for the generic "all traffic" outbound. Here's what one of the rules with both interfaces looks like: