High Availability Switch Config

Good morning,

I missed a critical step when designing our new HA upgrade, I completely forgot about the WAN side of things. To fix the issue, I came across this Sophos article and trying to follow how it is setup without using a Sophos switch.

https://docs.sophos.com/nsg/switch/help/en-us/haGuide/setupXGSHAwithswitch/index.html

Before I purchase any switch I am attempting to use one of my personal Juniper EX3200 to get the devices to work. I have created a new vlan on 3 ports, 2 for the WANS on 3100's and then the ISP connection itself. On the article it mentioned setting up Ingress filtering on the ports but not sure how to fully implement, has anyone setup a HA setup before and utilized a non Sophos switch to get the failover on the WAN? Or if it necessary, I don't want to jeopardize security for not rolling it out correctly. Thanks