Linux Advanced Routing Use Remote Gateway On LAN

I am trying to route a remote gateway so it can be used on the LAN to assign public IPs from a remote network. I have partially succeeded with some hacking around but cannot fully achieve what I want.

LAN A needs to use the remote gateway of WAN B.

Router on LAN A: br0 192.168.20.8 br0:0 8.8.8.1 (not the real IP of course). tap0 (OpenVPN tunnel attached to br0 bridge)

1. Client's on LAN A need to use 8.8.8.1.
2. Router on LAN needs to route packets for 8.8.8.1 through tap0

The problem is that Linux sees 8.8.8.1 as local and source based routing has failed to work so far.

I am fine with using iptables or source based routing tables if anyone can show me the solution.

Thanks for your help everyone!