Best practice network setup with OPNsense + FRITZ!Box

[c.monty]

Hi,

my ISP provides a static IP that is "passed through" the router (FRITZ!Box) on a dedicated port.
I'm planning to connect OPNsense router to this port as WAN.

There should be a DMZ provided by OPENsense where any webservice should be connected.

These webservices are running on virtual machines (KVM or LXC) hosted on a Proxmox server.
This server is connected to LAN of FRITZ!Box and should provide another LAN2 192.168.100.0/24.

The main question is how I should complete the network architecture in order to connect the webservices running on Proxmox server to DMZ provided by OPNsense?

Please check the attached graphic illustrating the network architecture for details.

Any advise is appreciated.