Re: Interfaces with SD-WAN setup
At least IPSEC cannot use a dynamic interface because you must give a specific remote gw on the tunnel's opposite end. You could only have one FQDN per interface in sdwan. Sdwan itself is not an option here because it depends on your rules and setings which interface in sdwan is used at which time. If you used FQDN on SDWAN as remote gw this would cause a load of drop outs or Flickering on the tunnels I guess.
I however prefer having one tunnel per wan for redundancy. I cope this with priority based routing. this works fine, has defined ends for remote gw and does tunnel fallback when the primary wan goes down to the second tunnel and back again.