Two WAN gateways, one for incoming VPNs and one for the rest

[PhreakShow]

Hi.

I recently got a second isp that provides internet over fibre. I also have a copper vdsl connection, both work fine.
The fibre offers 1gbit/s, copper is limited to 250mb/s but comes with a public ipv4 address, which the fibre network does not offer, only nat.

I need the public v4 address to access my network while I'm away, using opnsene's openvpn.
openvpn is configured and working fine.

Right now I am using just the vdsl connection for everything, using WAN. I want to configure a second interface and call it WAN2.

So the goal is: Configure opnsense to accept vpn connections over WAN, and use WAN2 for all the other traffic.

How do I do that? The tutorials or rather the documentation mentions failover or load balancing, but I want neither.