Creating additonal route pairs on a tunnel interface

[senseivita]

I'd like to add a second,third gateway for policies on an OpenVPN tap interface.

I don't know which is the right one.

Alias-type virtual addresses are not available because the "interface has no IP address, the message reads.

Other-type VIPs seem like they would work but I don't know if forwarding the traffic would be considered a service of the router/firewall since it's The service they provide. Never mind, they need the parent interface to have an address as well.

I tried adding the new addresses on the loopback on the remote router and another set on the loopback on the local router, let OSPF handle the rest. It was going well until I found out the loopback isn't selectable for gateways. I'm sure it would've worked though, earlier I configured ECMP adapting this guide from VyOS but the whole point is being able to select/the public interfaces (policy route) one router away from where they are.

How/where can I add the needed VIPs? I thought it would be easier making addresses up since it was OpenVPN but I was so wrong. :(

Any ideas? (that don't involve NAT)