I think you have 2 WAN Uplinks and want to push Guest flow to backup link.
You can go to SD WAN & traffic shaping --> Flow preferences --> source is Guest subnet, dest is any, preferred uplink is backup.
Thanks naturan for your response but my question is to push to specific public IP not to WAN 2.
For example, I have 5 public IPs and I want the guest to go though one of them specifically.
I think what you want to do is this. Hope it helps.
only have 1 Public IP for our small sites so I have no idea but you can open a case and Meraki can help you
Thank you but unfortunately it's not recommended to use
''A basic but insecure 1:1 NAT configuration can be set up to forward all traffic to the internal client. This should be configured when a 1:1 NAT needs to be made on a quick notice, but is not recommended due to security reasons. When all ports are forwarded to a client, attackers using a port scanner can target vulnerable services or gain access to the internal server.''
Maybe looking for more secured solution
What @natuan says is the only way you can do this I think. But then that WAN link has to have that dedicated IP of course.