Transparent Filtering Bridge allow all outgoing from a router inside of it ?

[mocs]

I have made myself a Transparent Filtering Bridge by following guide:
https://wiki.opnsense.org/manual/how-tos/transparent_bridge.html

My plan was to have a transparent filtering bridge allow incoming traffic to my router on just specific ports, this was no problem getting it working.

My problem is that I want to allow all outgoing traffic from my router threw the Transparent Filtering Bridge, my plan was to allow all outgoing with my WAN adress as source...

Its just that my Transparent Filtering Bridge does not know my WAN-adress due to the fact that my router inside of the OPNsense device has got the public IP-adress 

I was so happy having OPNsense on an APU4 - now I dont know how to make it work as I hoped

[hbc]

Why do you put the firewall in front of the exterior border router? You could switch them or use opnsense as as border router and assign public ip to it.
Why is it important to have public ip? IPS e.g. Just needs interface wanside and internal subnets.

[mocs]

I kind of really likes my router

My plan was to just add another layer of security without changing anything on the inside

Best thougt I have had so far is to allow my DDNs host as source, due to the fact I dont have a static IP. But then I have to allow update of the DDNS service as well and I am thinking this will probably lead to failures when my IPv4 adress is changed and everything is rebooted