Best Peplink product to route guest traffic to a specific WAN port

I have a system that needs dual wan with failover, but I would like to route all the guest traffic on the wireless LAN ( a separate system, not peplink ) to a specific port under normal operation. There will be corparte traffic on the wireless system as well, so I cannot use a physical port setting on the router.
I can use subnetting and static IPs on the company computers, and DHCP from the peplink router for the guest computers, if that helps.
Thank you.

The easiest way is maybe to segment the guest and corporate traffic into two subnets and have Peplink route all traffic from guest subnet to a certain WAN port by a Priority Outbound Policy.

QoS should be of help for a smoother user experience. And we can apply User Groups Bandwidth Control and Web Blocking to these subnets if we go for a Balance 380 or above.

Should be pretty straight-forward. Have a look at how it is done at our web admin demo page at http://www.peplink.com/demo/

I took a look at the demo and did not see how to specify a specific wan for a specific subnet traffic. Perhaps you could give me a little more detail?
This is for a new project, but I do have a balance 30 in service at another facility.

It is just outbound policy Kelly - we could use a Priority rule that says traffic from guest subnet e.g. 192.168.2.0/24 would go to WAN: GUEST and if it is not available go to WAN: CORPORATE.